Shell grep正则匹配中文

测试文本 demo_exe.c，内容如下，需要注意保存的编码格式，对输出到终端有影响：

我们中文操作系统ASNI默认是GBK的。

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include <string.h>
 4 #include <errno.h>
 5 #include <locale.h>
 6 #include <dlfcn.h>
 7 
 8 /*
 9  * export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/data/local/tmp; /data/local/tmp/demo_exe
10  */
11 int main(int argc, char** argv) {
12 // 这个是中文
13     void *handle = NULL;
14     char* locname = setlocale(LC_ALL, "");
15 // 这个是中文
16 //
17     if ((handle = dlopen(demo_dso_so, RTLD_NOW)) == NULL) {
18         printf("dlopen出错: %s\n", dlerror());
19     }
20     printf("@%s[%s]dlopen return handle = %#x.\n", __FILE__, __FUNCTION__, handle);
21 // 这个是
22 // 中文
23     return 0;
24 }

1、匹配特定文字：

$ grep -nP "\xE4\xB8\xAD\xE6\x96\x87|\xD6\xD0\xCE\xC4" ./demo_exe.c
12:// 这个是中文
15:// 这个是中文
22:// 中文

编码	中	文	在线码表
GBK	D6D0	CEC4	http://www.lhelper.org/tech/chinese_internal_code_specification_classified.txt
Unicode	4E2D	6587
UTF-8	%E4%B8%AD	%E6%96%87	http://wenku.baidu.com/link?url=DfbzjKLcRaQ7yVIA_EHVP7mKdVbkggq4hwkCmmO9uR76Jib_5Y1Y_h616NnI21XY_x85YZqN1SQBAdCFQjklS_

GBK码：中=D6D0，文=CEC4

Unicode码：中=4E2D，文=6587

UTF-8码：中=%E4%B8%AD，文=%E6%96%87

2、匹配特定范围文字

$ grep -nP "[\xB0\xA1-\xF7\xFE]+" /home/fangss/c/dynamic_share_object_test/demo_exe.c
12:// 这个是中文
15:// 这个是中文
18: printf("dlopen出错: %s\n", dlerror());
21:// 这个是
22:// 中文

范围：

● GBK/2: GB2312 汉字

B0 ０ １ ２ ３ ４ ５ ６ ７ ８ ９ Ａ Ｂ Ｃ Ｄ Ｅ Ｆ
Ａ 　 啊 阿 埃 挨 哎 唉 哀 皑 癌 蔼 矮 艾 碍 爱 隘
Ｂ 鞍 氨 安 俺 按 暗 岸 胺 案 肮 昂 盎 凹 敖 熬 翱
Ｃ 袄 傲 奥 懊 澳 芭 捌 扒 叭 吧 笆 八 疤 巴 拔 跋
Ｄ 靶 把 耙 坝 霸 罢 爸 白 柏 百 摆 佰 败 拜 稗 斑
Ｅ 班 搬 扳 般 颁 板 版 扮 拌 伴 瓣 半 办 绊 邦 帮
Ｆ 梆 榜 膀 绑 棒 磅 蚌 镑 傍 谤 苞 胞 包 褒 剥

。。。

F7 ０ １ ２ ３ ４ ５ ６ ７ ８ ９ Ａ Ｂ Ｃ Ｄ Ｅ Ｆ
Ａ 　 鳌 鳍 鳎 鳏 鳐 鳓 鳔 鳕 鳗 鳘 鳙 鳜 鳝 鳟 鳢
Ｂ 靼 鞅 鞑 鞒 鞔 鞯 鞫 鞣 鞲 鞴 骱 骰 骷 鹘 骶 骺
Ｃ 骼 髁 髀 髅 髂 髋 髌 髑 魅 魃 魇 魉 魈 魍 魑 飨
Ｄ 餍 餮 饕 饔 髟 髡 髦 髯 髫 髻 髭 髹 鬈 鬏 鬓 鬟
Ｅ 鬣 麽 麾 縻 麂 麇 麈 麋 麒 鏖 麝 麟 黛 黜 黝 黠
Ｆ 黟 黢 黩 黧 黥 黪 黯 鼢 鼬 鼯 鼹 鼷 鼽 鼾 齄

正则表达式

正则表达式30分钟入门教程

转载来源版本：v2.33 (2013-1-10) 作者：deerchao

Get XRegExp 2.0: minified (3.5 KB gzipped), or with comments. Get the full package or the latest development build at GitHub.

Java中正则，中链接 Regular Expressions of Java Tutorial

Java正则表达式教程

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                            <ul>
                                <li style=" display:none;"><input type="checkbox" checked="checked" id="toolG"><label for="toolG">全局</label></li>
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                                <textarea spellcheck="false" tabindex="2" rows="10" cols="100" id="inputText" style="height: 180px; margin-left: 0px; width: 856px;">tool.chinaz.com|888|http://www.cnblogs.com/Fang3s/p/4338103.html</textarea>
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                // http://tool.chinaz.com/template/default/js/reg.js
                function $(el) { if (el.nodeName) return el; if (typeof el === "string") return document.getElementById(el); return false }; var trim = function () { var lSpace = /^\s\s*/, rSpace = /\s\s*$/; return function (str) { return str.replace(lSpace, "").replace(rSpace, "") } }(); function replaceHtml(el, html) { var oldEl = $(el); var newEl = oldEl.cloneNode(false); newEl.innerHTML = html; oldEl.parentNode.replaceChild(newEl, oldEl); return newEl }; function replaceOuterHtml(el, html) { el = replaceHtml(el, ""); if (el.outerHTML) { var id = el.id, className = el.className, nodeName = el.nodeName; el.outerHTML = "<" + nodeName + " id=\"" + id + "\" class=\"" + className + "\">" + html + "</" + nodeName + ">"; el = $(id) } else { el.innerHTML = html }; return el }; function getElementsByClassName(className, tagName, parentNode) { var els = ($(parentNode) || document).getElementsByTagName(tagName || "*"), results = []; for (var i = 0; i < els.length; i++) { if (hasClass(className, els[i])) results.push(els[i]) }; return results }; function hasClass(className, el) { return XRegExp.cache("(?:^|\\s)" + className + "(?:\\s|$)").test($(el).className) }; function addClass(className, el) { el = $(el); if (!hasClass(className, el)) { el.className = trim(el.className + " " + className) } }; function removeClass(className, el) { el = $(el); el.className = trim(el.className.replace(XRegExp.cache("(?:^|\\s)" + className + "(?:\\s|$)", "g"), " ")) }; function toggleClass(className, el) { if (hasClass(className, el)) { removeClass(className, el) } else { addClass(className, el) } }; function swapClass(oldClass, newClass, el) { removeClass(oldClass, el); addClass(newClass, el) }; function replaceSelection(textbox, str) { if (textbox.setSelectionRange) { var start = textbox.selectionStart, end = textbox.selectionEnd, offset = (start + str.length); textbox.value = (textbox.value.substring(0, start) + str + textbox.value.substring(end)); textbox.setSelectionRange(offset, offset) } else if (document.selection) { var range = document.selection.createRange(); range.text = str; range.select() } }; function extend(to, from) { for (var property in from) to[property] = from[property]; return to }; function purge(d) { var a = d.attributes, i, l, n; if (a) { l = a.length; for (i = 0; i < l; i += 1) { n = a[i].name; if (typeof d[n] === \'function\') { d[n] = null } } }; a = d.childNodes; if (a) { l = a.length; for (i = 0; i < l; i += 1) { purge(d.childNodes[i]) } } }; var isWebKit = navigator.userAgent.indexOf("WebKit") > -1, isIE, isIE6 = isIE && !window.XMLHttpRequest; var RegexPal = { fields: { search: new SmartField("search"), input: new SmartField("input"), options: { flags: { g: $("toolG"), i: $("toolI"), m: $("toolM"), s: $("toolS") }, highlightSyntax: $("highSyntax"), highlightMatches: $("highMatch"), invertMatches: $("invertMatch") } } }; extend(RegexPal, function () { var f = RegexPal.fields, o = f.options; return { highlightMatches: function () { var re = { matchPair: /`~\{((?:[^}]+|\}(?!~`))*)\}~`((?:[^`]+|`(?!~\{(?:[^}]+|\}(?!~`))*\}~`))*)(?:`~\{((?:[^}]+|\}(?!~`))*)\}~`)?/g, sansTrailingAlternator: /^(?:[^\\|]+|\\[\S\s]?|\|(?=[\S\s]))*/ }; return function () { var search = String(f.search.textbox.value), input = String(f.input.textbox.value); if (XRegExp.cache(\'<[bB] class="?err"?>\').test(f.search.bg.innerHTML) || (!search.length && !o.invertMatches.checked) || !o.highlightMatches.checked) { f.input.clearBg(); return }; try { var searchRegex = new XRegExp(re.sansTrailingAlternator.exec(search)[0], (o.flags.g.checked ? "g" : "") + (o.flags.i.checked ? "i" : "") + (o.flags.m.checked ? "m" : "") + (o.flags.s.checked ? "s" : "")) } catch (err) { f.input.clearBg(); return }; if (o.invertMatches.checked) { var output = ("`~{" + input.replace(searchRegex, "}~`$&`~{") + "}~`").replace(XRegExp.cache("`~\\{\\}~`|\\}~``~\\{", "g"), "") } else { var output = input.replace(searchRegex, "`~{$&}~`") }; output = output.replace(XRegExp.cache("[<&>]", "g"), "_").replace(re.matchPair, "<b>$1</b>$2<i>$3</i>"); f.input.setBgHtml(output) } }(), highlightSearchSyntax: function () { if (o.highlightSyntax.checked) { f.search.setBgHtml(parseRegex(f.search.textbox.value)) } else { f.search.clearBg() } } } }()); var parseRegex = function () { var re = { regexToken: /\[\^?]?(?:[^\\\]]+|\\[\S\s]?)*]?|\\(?:0(?:[0-3][0-7]{0,2}|[4-7][0-7]?)?|[1-9][0-9]*|x[0-9A-Fa-f]{2}|u[0-9A-Fa-f]{4}|c[A-Za-z]|[\S\s]?)|\((?:\?[:=!]?)?|(?:[?*+]|\{[0-9]+(?:,[0-9]*)?\})\??|[^.?*+^${[()|\\]+|./g, characterClassParts: /^(<opening>\[\^?)(<contents>]?(?:[^\\\]]+|\\[\S\s]?)*)(<closing>]?)$/.addFlags("k"), characterClassToken: /[^\\-]+|-|\\(?:[0-3][0-7]{0,2}|[4-7][0-7]?|x[0-9A-Fa-f]{2}|u[0-9A-Fa-f]{4}|c[A-Za-z]|[\S\s]?)/g, quantifier: /^(?:[?*+]|\{[0-9]+(?:,[0-9]*)?\})\??$/ }, type = { NONE: 0, RANGE_HYPHEN: 1, METACLASS: 2, ALTERNATOR: 3 }; function errorStr(str) { return \'<b class="err">\' + str + \'</b>\' }; function getTokenCharCode(token) { if (token.length > 1 && token.charAt(0) === "\\") { var t = token.slice(1); if (XRegExp.cache("^c[A-Za-z]$").test(t)) { return "ABCDEFGHIJKLMNOPQRSTUVWXYZ".indexOf(t.charAt(1).toUpperCase()) + 1 } else if (XRegExp.cache("^(?:x[0-9A-Fa-f]{2}|u[0-9A-Fa-f]{4})$").test(t)) { return parseInt(t.slice(1), 16) } else if (XRegExp.cache("^(?:[0-3][0-7]{0,2}|[4-7][0-7]?)$").test(t)) { return parseInt(t, 8) } else if (t.length === 1 && "cuxDdSsWw".indexOf(t) > -1) { return false } else if (t.length === 1) { switch (t) { case "b": return 8; case "f": return 12; case "n": return 10; case "r": return 13; case "t": return 9; case "v": return 11; default: return t.charCodeAt(0) } } } else if (token !== "\\") { return token.charCodeAt(0) }; return false }; function parseCharacterClass(value) { var output = "", parts = re.characterClassParts.exec(value), parser = re.characterClassToken, lastToken = { rangeable: false, type: type.NONE }, match, m; output += parts.closing ? parts.opening : errorStr(parts.opening); while (match = parser.exec(parts.contents)) { m = match[0]; if (m.charAt(0) === "\\") { if (XRegExp.cache("^\\\\[cux]$").test(m)) { output += errorStr(m); lastToken = { rangeable: lastToken.type !== type.RANGE_HYPHEN } } else if (XRegExp.cache("^\\\\[dsw]$", "i").test(m)) { output += "<b>" + m + "</b>"; lastToken = { rangeable: lastToken.type !== type.RANGE_HYPHEN, type: type.METACLASS } } else if (m === "\\") { output += errorStr(m) } else { output += "<b>" + m.replace(XRegExp.cache("[<&>]"), "_") + "</b>"; lastToken = { rangeable: lastToken.type !== type.RANGE_HYPHEN, charCode: getTokenCharCode(m) } } } else if (m === "-") { if (lastToken.rangeable) { var lastIndex = parser.lastIndex, nextToken = parser.exec(parts.contents); if (nextToken) { var nextTokenCharCode = getTokenCharCode(nextToken[0]); if ((nextTokenCharCode !== false && lastToken.charCode > nextTokenCharCode) || lastToken.type === type.METACLASS || XRegExp.cache("^\\\\[dsw]$", "i").test(nextToken[0])) { output += errorStr("-") } else { output += "<u>-</u>" }; lastToken = { rangeable: false, type: type.RANGE_HYPHEN } } else { if (parts.closing) { output += "-" } else { output += "<u>-</u>"; break } }; parser.lastIndex = lastIndex } else { output += "-"; lastToken = { rangeable: lastToken.type !== type.RANGE_HYPHEN } } } else { output += m.replace(XRegExp.cache("[<&>]", "g"), "_"); lastToken = { rangeable: (m.length > 1 || lastToken.type !== type.RANGE_HYPHEN), charCode: m.charCodeAt(m.length - 1) } } }; return output + parts.closing }; return function (value) { var output = "", capturingGroupCount = 0, groupStyleDepth = 0, openGroups = [], lastToken = { quantifiable: false, type: type.NONE }, match, m; function groupStyleStr(str) { return \'<b class="g\' + groupStyleDepth + \'">\' + str + \'</b>\' }; while (match = re.regexToken.exec(value)) { m = match[0]; switch (m.charAt(0)) { case "[": output += "<i>" + parseCharacterClass(m) + "</i>"; lastToken = { quantifiable: true }; break; case "(": if (m.length === 2) { output += errorStr(m) } else { if (m.length === 1) capturingGroupCount++; groupStyleDepth = groupStyleDepth === 5 ? 1 : groupStyleDepth + 1; openGroups.push({ index: output.length + 14, opening: m }); output += groupStyleStr(m) }; lastToken = { quantifiable: false }; break; case ")": if (!openGroups.length) { output += errorStr(")"); lastToken = { quantifiable: false } } else { output += groupStyleStr(")"); lastToken = { quantifiable: !XRegExp.cache("^[=!]").test(openGroups[openGroups.length - 1].opening.charAt(2)), style: "g" + groupStyleDepth }; groupStyleDepth = groupStyleDepth === 1 ? 5 : groupStyleDepth - 1; openGroups.pop() }; break; case "\\": if (XRegExp.cache("^[1-9]").test(m.charAt(1))) { var nonBackrefDigits = "", num = +m.slice(1); while (num > capturingGroupCount) { nonBackrefDigits = XRegExp.cache("[0-9]$").exec(num)[0] + nonBackrefDigits; num = Math.floor(num / 10) }; if (num > 0) { output += "<b>\\" + num + "</b>" + nonBackrefDigits } else { var parts = XRegExp.cache("^\\\\([0-3][0-7]{0,2}|[4-7][0-7]?|[89])([0-9]*)").exec(m); output += "<b>\\" + parts[1] + "</b>" + parts[2] } } else if (XRegExp.cache("^[0bBcdDfnrsStuvwWx]").test(m.charAt(1))) { if (XRegExp.cache("^\\\\[cux]$").test(m)) { output += errorStr(m); lastToken = { quantifiable: false }; break }; output += "<b>" + m + "</b>"; if ("bB".indexOf(m.charAt(1)) > -1) { lastToken = { quantifiable: false }; break } } else if (m === "\\") { output += errorStr(m) } else { output += m.replace(XRegExp.cache("[<&>]"), "_") }; lastToken = { quantifiable: true }; break; default: if (re.quantifier.test(m)) { if (lastToken.quantifiable) { var interval = XRegExp.cache("^\\{([0-9]+)(?:,([0-9]*))?").exec(m); if (interval && ((interval[1] > 65535) || (interval[2] && ((interval[2] > 65535) || (+interval[1] > +interval[2]))))) { output += errorStr(m) } else { output += (lastToken.style ? \'<b class="\' + lastToken.style + \'">\' : \'<b>\') + m + \'</b>\' } } else { output += errorStr(m) }; lastToken = { quantifiable: false } } else if (m === "|") { if (lastToken.type === type.NONE || (lastToken.type === type.ALTERNATOR && !openGroups.length)) { output += errorStr(m) } else { output += openGroups.length ? groupStyleStr("|") : "<b>|</b>" }; lastToken = { quantifiable: false, type: type.ALTERNATOR } } else if ("^$".indexOf(m) > -1) { output += "<b>" + m + "</b>"; lastToken = { quantifiable: false } } else if (m === ".") { output += "<b>.</b>"; lastToken = { quantifiable: true } } else { output += m.replace(XRegExp.cache("[<&>]", "g"), "_"); lastToken = { quantifiable: true } } } }; var numCharsAdded = 0; for (var i = 0; i < openGroups.length; i++) { var errorIndex = openGroups[i].index + numCharsAdded; output = (output.slice(0, errorIndex) + errorStr(openGroups[i].opening) + output.slice(errorIndex + openGroups[i].opening.length)); numCharsAdded += errorStr("").length }; return output } }(); function SmartField(el) { el = $(el); var textboxEl = el.getElementsByTagName("textarea")[0], bgEl = document.createElement("pre"); textboxEl.id = el.id + "Text"; bgEl.id = el.id + "Bg"; el.insertBefore(bgEl, textboxEl); textboxEl.onkeydown = function (e) { SmartField.prototype._onKeyDown(e) }; textboxEl.onkeyup = function (e) { SmartField.prototype._onKeyUp(e) }; if (isIE) el.style.overflowX = "hidden"; if (isWebKit) textboxEl.style.marginLeft = 0; this.field = el; this.textbox = textboxEl; this.bg = bgEl }; extend(SmartField.prototype, { setBgHtml: function (html) { html = html.replace(XRegExp.cache("^\\n"), "\n\n"); this.bg = replaceOuterHtml(this.bg, html + "<br>&nbsp;"); this.setDimensions() }, clearBg: function () { this.setBgHtml(this.textbox.value.replace(XRegExp.cache("[<&>]", "g"), "_")) }, setDimensions: function () { this.textbox.style.width = ""; var scrollWidth = this.textbox.scrollWidth, offsetWidth = this.textbox.offsetWidth; this.textbox.style.width = (scrollWidth === offsetWidth ? offsetWidth - 1 : scrollWidth + 8) + "px"; this.textbox.style.height = Math.max(this.bg.offsetHeight, this.field.offsetHeight - 2) + "px" }, _onKeyDown: function (e) { e = e || event; if (!this._filterKeys(e)) return false; var srcEl = e.srcElement || e.target; switch (srcEl) { case RegexPal.fields.search.textbox: setTimeout(function () { RegexPal.highlightSearchSyntax.call(RegexPal) }, 0); break }; if (isWebKit && srcEl.selectionEnd === srcEl.value.length) { srcEl.parentNode.scrollTop = srcEl.scrollHeight }; this._testKeyHold(e) }, _onKeyUp: function (e) { e = e || event; var srcEl = e.srcElement || e.target; this._keydownCount = 0; if (this._matchOnKeyUp) { this._matchOnKeyUp = false; switch (srcEl) { case RegexPal.fields.search.textbox: case RegexPal.fields.input.textbox: RegexPal.highlightMatches(); break } } }, _testKeyHold: function (e) { var srcEl = e.srcElement || e.target; this._keydownCount++; if (this._keydownCount > 2) { RegexPal.fields.input.clearBg(); this._matchOnKeyUp = true } else { switch (srcEl) { case RegexPal.fields.search.textbox: case RegexPal.fields.input.textbox: setTimeout(function () { RegexPal.highlightMatches.call(RegexPal) }, 0); break } } }, _filterKeys: function (e) { var srcEl = e.srcElement || e.target, f = RegexPal.fields; if (this._deadKeys.indexOf(e.keyCode) > -1) return false; if ((e.keyCode === 9) && (srcEl === f.input.textbox || (srcEl === f.search.textbox && !e.shiftKey))) { if (srcEl === f.input.textbox) { if (e.shiftKey) { f.search.textbox.focus() } else { replaceSelection(srcEl, "\t"); if (window.opera) setTimeout(function () { srcEl.focus() }, 0) } } else { f.input.textbox.focus() }; if (e.preventDefault) e.preventDefault(); else e.returnValue = false }; return true }, _matchOnKeyUp: false, _keydownCount: 0, _deadKeys: [16, 17, 18, 19, 20, 27, 33, 34, 35, 36, 37, 38, 39, 40, 44, 45, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 144, 145] }); (function () { var f = RegexPal.fields, o = f.options; onresize = function (e) { var isIE1 = !!window.ActiveXObject; var isIE61 = isIE1 && !window.XMLHttpRequest; if (isIE61) f.input.field.style.height = Math.max((window.innerHeight || document.documentElement.clientHeight) - 310, 180) + "px"; else f.input.field.style.height = Math.max((window.innerHeight || document.documentElement.clientHeight) - 610, 180) + "px"; f.search.setDimensions(); f.input.setDimensions() }; onresize(); RegexPal.highlightSearchSyntax(); RegexPal.highlightMatches(); for (var flag in o.flags) { o.flags[flag].onclick = RegexPal.highlightMatches }; o.highlightSyntax.onclick = RegexPal.highlightSearchSyntax; o.highlightMatches.onclick = RegexPal.highlightMatches; o.invertMatches.onclick = RegexPal.highlightMatches; function makeResetter(field) { return function () { field.clearBg(); field.textbox.value = ""; field.textbox.onfocus = null } }; if (f.search.textbox.value == "(\\w+\\.){2}\\w+") { f.search.textbox.onfocus = makeResetter(f.search) }; if (f.input.textbox.value === "tool.chinaz.com|888") { f.input.textbox.onfocus = makeResetter(f.input) } })();
            </script>

            <div class="box">
                <div id="b_14">
                    <h1>工具简介</h1>
                    <div class="box1">
                        <span class="info2" style=" font-size: 14px; line-height: 24px; text-align: left;white-space:normal; width:860px;overflow:hidden;">
                            <span style=" font-weight:bold; color:Red;">正则表达式到底是什么东西？</span><br>在编写处理字符串的程序或网页时，经常会有查找符合某些复杂规则的字符串的需要。正则表达式就是用于描述这些规则的工具。换句话说，正则表达式就是记录文本规则的代码。<br><span style=" font-weight:bold; color:Red;">常用元字符</span><br><table cellspacing="0"><thead><tr><th scope="col">代码</th><th scope="col">说明</th></tr></thead><tbody><tr><td><span class="code">.</span></td><td><span class="desc">匹配除换行符以外的任意字符</span></td></tr><tr><td><span class="code">\w</span></td><td><span class="desc">匹配字母或数字或下划线或汉字</span></td></tr><tr><td><span class="code">\s</span></td><td><span class="desc">匹配任意的空白符</span></td></tr><tr><td><span class="code">\d</span></td><td><span class="desc">匹配数字</span></td></tr><tr><td><span class="code">\b</span></td><td><span class="desc">匹配单词的开始或结束</span></td></tr><tr><td><span class="code">^</span></td><td><span class="desc">匹配字符串的开始</span></td></tr><tr><td><span class="code">$</span></td><td><span class="desc">匹配字符串的结束</span></td></tr></tbody></table><br><span style=" font-weight:bold; color:Red;">常用限定符</span><br><table cellspacing="0"><thead><tr><th scope="col">代码/语法</th><th scope="col">说明</th></tr></thead><tbody><tr><td><span class="code">*</span></td><td><span class="desc">重复零次或更多次</span></td></tr><tr><td><span class="code">+</span></td><td><span class="desc">重复一次或更多次</span></td></tr><tr><td><span class="code">?</span></td><td><span class="desc">重复零次或一次</span></td></tr><tr><td><span class="code">{n}</span></td><td><span class="desc">重复n次</span></td></tr><tr><td><span class="code">{n,}</span></td><td><span class="desc">重复n次或更多次</span></td></tr><tr><td><span class="code">{n,m}</span></td><td><span class="desc">重复n到m次</span></td></tr></tbody></table><br><span style=" font-weight:bold; color:Red;">常用反义词</span><br><table cellspacing="0"><thead><tr><th scope="col">代码/语法</th><th scope="col">说明</th></tr></thead><tbody><tr><td><span class="code">\W</span></td><td><span class="desc">匹配任意不是字母，数字，下划线，汉字的字符</span></td></tr><tr><td><span class="code">\S</span></td><td><span class="desc">匹配任意不是空白符的字符</span></td></tr><tr><td><span class="code">\D</span></td><td><span class="desc">匹配任意非数字的字符</span></td></tr><tr><td><span class="code">\B</span></td><td><span class="desc">匹配不是单词开头或结束的位置</span></td></tr><tr><td><span class="code">[^x]</span></td><td><span class="desc">匹配除了x以外的任意字符</span></td></tr><tr><td><span class="code">[^aeiou]</span></td><td><span class="desc">匹配除了aeiou这几个字母以外的任意字符</span></td></tr></tbody></table><br>
                        </span>
                    </div>
                </div>
                <div style=" height:5px;"></div>
            </div>
        </div>
    </div>
</body>
</html>-->

正则表达式在线测试

/* utf-8: 0xc0, 0xe0, 0xf0, 0xf8, 0xfc

char str[] = "hello,中文字", len = strlen(str);
int utf8CharLen;
for (int i = 0, utf8CharLen; i < len; i += utf8CharLen)
{
utf8CharLen = BYTE_WIDTH_UTF8(str[i]);
printf("str[%d] is a word character with %d bytes\n", i, utf8CharLen);
}
*/
unsigned char mblen_table_utf8[] =
{
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
    4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 1, 1
};

#define BYTE_WIDTH_UTF8(x)  mblen_table_utf8[(unsigned char)(x)]

int _tmain(int argc, _TCHAR* argv[])
{
    char str[] = "hello,中文字", len = strlen(str);
    int utf8CharLen;
    for (int i = 0, utf8CharLen; i < len; i += utf8CharLen)
    {
        utf8CharLen = BYTE_WIDTH_UTF8(str[i]);
        printf("str[%d] is a word character with %d bytes\n", i, utf8CharLen);
    }
    getchar();
}

下面

比如某二进制字节是UTF-8编码的字符串的实际字节，则作用和public String(byte bytes[], String charsetName)取codePoint类似

/* UTF8 utilities */

/* This parses a UTF8 string one character at a time. It is passed a pointer
 * to the string and the length of the string. It sets \'value\' to the value of
 * the current character. It returns the number of characters read or a
 * negative error code:
 * -1 = string too short
 * -2 = illegal character
 * -3 = subsequent characters not of the form 10xxxxxx
 * -4 = character encoded incorrectly (not minimal length).
 */

int UTF8_getc(const unsigned char *str, int len, unsigned long *val)
{
    const unsigned char *p;
    unsigned long value;
    int ret;
    if(len <= 0) return 0;
    p = str;

    /* Check syntax and work out the encoded value (if correct) */
    if((*p & 0x80) == 0) {
        value = *p++ & 0x7f;
        ret = 1;
    } else if((*p & 0xe0) == 0xc0) {
        if(len < 2) return -1;
        if((p[1] & 0xc0) != 0x80) return -3;
        value = (*p++ & 0x1f) << 6;
        value |= *p++ & 0x3f;
        if(value < 0x80) return -4;
        ret = 2;
    } else if((*p & 0xf0) == 0xe0) {
        if(len < 3) return -1;
        if( ((p[1] & 0xc0) != 0x80)
           || ((p[2] & 0xc0) != 0x80) ) return -3;
        value = (*p++ & 0xf) << 12;
        value |= (*p++ & 0x3f) << 6;
        value |= *p++ & 0x3f;
        if(value < 0x800) return -4;
        ret = 3;
    } else if((*p & 0xf8) == 0xf0) {
        if(len < 4) return -1;
        if( ((p[1] & 0xc0) != 0x80)
           || ((p[2] & 0xc0) != 0x80)
           || ((p[3] & 0xc0) != 0x80) ) return -3;
        value = ((unsigned long)(*p++ & 0x7)) << 18;
        value |= (*p++ & 0x3f) << 12;
        value |= (*p++ & 0x3f) << 6;
        value |= *p++ & 0x3f;
        if(value < 0x10000) return -4;
        ret = 4;
    } else if((*p & 0xfc) == 0xf8) {
        if(len < 5) return -1;
        if( ((p[1] & 0xc0) != 0x80)
           || ((p[2] & 0xc0) != 0x80)
           || ((p[3] & 0xc0) != 0x80)
           || ((p[4] & 0xc0) != 0x80) ) return -3;
        value = ((unsigned long)(*p++ & 0x3)) << 24;
        value |= ((unsigned long)(*p++ & 0x3f)) << 18;
        value |= ((unsigned long)(*p++ & 0x3f)) << 12;
        value |= (*p++ & 0x3f) << 6;
        value |= *p++ & 0x3f;
        if(value < 0x200000) return -4;
        ret = 5;
    } else if((*p & 0xfe) == 0xfc) {
        if(len < 6) return -1;
        if( ((p[1] & 0xc0) != 0x80)
           || ((p[2] & 0xc0) != 0x80)
           || ((p[3] & 0xc0) != 0x80)
           || ((p[4] & 0xc0) != 0x80)
           || ((p[5] & 0xc0) != 0x80) ) return -3;
        value = ((unsigned long)(*p++ & 0x1)) << 30;
        value |= ((unsigned long)(*p++ & 0x3f)) << 24;
        value |= ((unsigned long)(*p++ & 0x3f)) << 18;
        value |= ((unsigned long)(*p++ & 0x3f)) << 12;
        value |= (*p++ & 0x3f) << 6;
        value |= *p++ & 0x3f;
        if(value < 0x4000000) return -4;
        ret = 6;
    } else return -2;
    *val = value;
    return ret;
}

/* This takes a character \'value\' and writes the UTF8 encoded value in
 * \'str\' where \'str\' is a buffer containing \'len\' characters. Returns
 * the number of characters written or -1 if \'len\' is too small. \'str\' can
 * be set to NULL in which case it just returns the number of characters.
 * It will need at most 6 characters.
 */

int UTF8_putc(unsigned char *str, int len, unsigned long value)
{
    if(!str) len = 6;    /* Maximum we will need */
    else if(len <= 0) return -1;
    if(value < 0x80) {
        if(str) *str = (unsigned char)value;
        return 1;
    }
    if(value < 0x800) {
        if(len < 2) return -1;
        if(str) {
            *str++ = (unsigned char)(((value >> 6) & 0x1f) | 0xc0);
            *str = (unsigned char)((value & 0x3f) | 0x80);
        }
        return 2;
    }
    if(value < 0x10000) {
        if(len < 3) return -1;
        if(str) {
            *str++ = (unsigned char)(((value >> 12) & 0xf) | 0xe0);
            *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
            *str = (unsigned char)((value & 0x3f) | 0x80);
        }
        return 3;
    }
    if(value < 0x200000) {
        if(len < 4) return -1;
        if(str) {
            *str++ = (unsigned char)(((value >> 18) & 0x7) | 0xf0);
            *str++ = (unsigned char)(((value >> 12) & 0x3f) | 0x80);
            *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
            *str = (unsigned char)((value & 0x3f) | 0x80);
        }
        return 4;
    }
    if(value < 0x4000000) {
        if(len < 5) return -1;
        if(str) {
            *str++ = (unsigned char)(((value >> 24) & 0x3) | 0xf8);
            *str++ = (unsigned char)(((value >> 18) & 0x3f) | 0x80);
            *str++ = (unsigned char)(((value >> 12) & 0x3f) | 0x80);
            *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
            *str = (unsigned char)((value & 0x3f) | 0x80);
        }
        return 5;
    }
    if(len < 6) return -1;
    if(str) {
        *str++ = (unsigned char)(((value >> 30) & 0x1) | 0xfc);
        *str++ = (unsigned char)(((value >> 24) & 0x3f) | 0x80);
        *str++ = (unsigned char)(((value >> 18) & 0x3f) | 0x80);
        *str++ = (unsigned char)(((value >> 12) & 0x3f) | 0x80);
        *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
        *str = (unsigned char)((value & 0x3f) | 0x80);
    }
    return 6;
}

http://www.leonerd.org.uk/code/libtickit/doc/

tickit_string_putchar(3)	tickit_string_putchar - append a UTF-8 encoded codepoint to a buffer
tickit_string_seqlen(3)	tickit_string_seqlen - determine the length of a UTF-8 codepoint encoding

static int next_utf8(const char *str, size_t len, uint32_t *cp)
{
  unsigned char b0 = (str++)[0];
  int nbytes;

  if(!len)
    return -1;

  if(!b0)
    return -1;
  else if(b0 < 0x80) { // ASCII
    *cp = b0; return 1;
  }
  else if(b0 < 0xc0) // C1 or continuation
    return -1;
  else if(b0 < 0xe0) {
    nbytes = 2; *cp = b0 & 0x1f;
  }
  else if(b0 < 0xf0) {
    nbytes = 3; *cp = b0 & 0x0f;
  }
  else if(b0 < 0xf8) {
    nbytes = 4; *cp = b0 & 0x07;
  }
  else
    return -1;

  if(len < nbytes)
    return -1;

  for(int i = 1; i < nbytes; i++) {
    b0 = (str++)[0];
    if(!b0)
      return -1;

    *cp <<= 6;
    *cp |= b0 & 0x3f;
  }

  return nbytes;
}

int tickit_string_seqlen(long codepoint)
{
  if(codepoint < 0x0000080) return 1;
  if(codepoint < 0x0000800) return 2;
  if(codepoint < 0x0010000) return 3;
  if(codepoint < 0x0200000) return 4;
  if(codepoint < 0x4000000) return 5;
  return 6;
}

size_t tickit_string_putchar(char *str, size_t len, long codepoint)
{
  int nbytes = tickit_string_seqlen(codepoint);
  if(!str)
    return nbytes;
  if(len < nbytes)
    return -1;

  // This is easier done backwards
  int b = nbytes;
  while(b > 1) {
    b--;
    str[b] = 0x80 | (codepoint & 0x3f);
    codepoint >>= 6;
  }

  switch(nbytes) {
    case 1: str[0] =        (codepoint & 0x7f); break;
    case 2: str[0] = 0xc0 | (codepoint & 0x1f); break;
    case 3: str[0] = 0xe0 | (codepoint & 0x0f); break;
    case 4: str[0] = 0xf0 | (codepoint & 0x07); break;
    case 5: str[0] = 0xf8 | (codepoint & 0x03); break;
    case 6: str[0] = 0xfc | (codepoint & 0x01); break;
  }

  return nbytes;
}

由codePoint计算这个值转化为UTF8应该占几个字节

/* The following functions copied and adapted from libtermkey
 *
 * http://www.leonerd.org.uk/code/libtermkey/
 */
static inline unsigned int utf8_seqlen(long codepoint)
{
  if(codepoint < 0x0000080) return 1;
  if(codepoint < 0x0000800) return 2;
  if(codepoint < 0x0010000) return 3;
  if(codepoint < 0x0200000) return 4;
  if(codepoint < 0x4000000) return 5;
  return 6;
}

/* Does NOT NUL-terminate the buffer */
static int fill_utf8(long codepoint, char *str)
{
  int nbytes = utf8_seqlen(codepoint);

  // This is easier done backwards
  int b = nbytes;
  while(b > 1) {
    b--;
    str[b] = 0x80 | (codepoint & 0x3f);
    codepoint >>= 6;
  }

  switch(nbytes) {
    case 1: str[0] =        (codepoint & 0x7f); break;
    case 2: str[0] = 0xc0 | (codepoint & 0x1f); break;
    case 3: str[0] = 0xe0 | (codepoint & 0x0f); break;
    case 4: str[0] = 0xf0 | (codepoint & 0x07); break;
    case 5: str[0] = 0xf8 | (codepoint & 0x03); break;
    case 6: str[0] = 0xfc | (codepoint & 0x01); break;
  }

  return nbytes;
}
/* end copy */

liblinebreak-2.0 : Line breaking in a Unicode sequence. Designed to be used in a generic text renderer.

typedef unsigned char    utf8_t;        /**< Type for UTF-8 data points */
typedef unsigned short    utf16_t;    /**< Type for UTF-16 data points */
typedef unsigned int    utf32_t;    /**< Type for UTF-32 data points */

/**
 * Gets the next Unicode character in a UTF-8 sequence.  The index will
 * be advanced to the next complete character, unless the end of string
 * is reached in the middle of a UTF-8 sequence.
 *
 * @param[in]     s        input UTF-8 string
 * @param[in]     len    length of the string in bytes
 * @param[in,out] ip    pointer to the index
 * @return                the Unicode character beginning at the index; or
 *                        #EOS if end of input is encountered
 */
utf32_t lb_get_next_char_utf8(
        const utf8_t *s,
        size_t len,
        size_t *ip)
{
    utf8_t ch;
    utf32_t res;

    assert(*ip <= len);
    if (*ip == len)
        return EOS;
    ch = s[*ip];

    if (ch < 0xC2 || ch > 0xF4)
    {    /* One-byte sequence, tail (should not occur), or invalid */
        *ip += 1;
        return ch;
    }
    else if (ch < 0xE0)
    {    /* Two-byte sequence */
        if (*ip + 2 > len)
            return EOS;
        res = ((ch & 0x1F) << 6) + (s[*ip + 1] & 0x3F);
        *ip += 2;
        return res;
    }
    else if (ch < 0xF0)
    {    /* Three-byte sequence */
        if (*ip + 3 > len)
            return EOS;
        res = ((ch & 0x0F) << 12) +
              ((s[*ip + 1] & 0x3F) << 6) +
              ((s[*ip + 2] & 0x3F));
        *ip += 3;
        return res;
    }
    else
    {    /* Four-byte sequence */
        if (*ip + 4 > len)
            return EOS;
        res = ((ch & 0x07) << 18) +
              ((s[*ip + 1] & 0x3F) << 12) +
              ((s[*ip + 2] & 0x3F) << 6) +
              ((s[*ip + 3] & 0x3F));
        *ip += 4;
        return res;
    }
}

/**
 * Gets the next Unicode character in a UTF-16 sequence.  The index will
 * be advanced to the next complete character, unless the end of string
 * is reached in the middle of a UTF-16 surrogate pair.
 *
 * @param[in]     s        input UTF-16 string
 * @param[in]     len    length of the string in words
 * @param[in,out] ip    pointer to the index
 * @return                the Unicode character beginning at the index; or
 *                        #EOS if end of input is encountered
 */
utf32_t lb_get_next_char_utf16(
        const utf16_t *s,
        size_t len,
        size_t *ip)
{
    utf16_t ch;

    assert(*ip <= len);
    if (*ip == len)
        return EOS;
    ch = s[(*ip)++];

    if (ch < 0xD800 || ch > 0xDBFF)
    {    /* If the character is not a high surrogate */
        return ch;
    }
    if (*ip == len)
    {    /* If the input ends here (an error) */
        --(*ip);
        return EOS;
    }
    if (s[*ip] < 0xDC00 || s[*ip] > 0xDFFF)
    {    /* If the next character is not the low surrogate (an error) */
        return ch;
    }
    /* Return the constructed character and advance the index again */
    return (((utf32_t)ch & 0x3FF) << 10) + (s[(*ip)++] & 0x3FF) + 0x10000;
}

/**
 * Gets the next Unicode character in a UTF-32 sequence.  The index will
 * be advanced to the next character.
 *
 * @param[in]     s        input UTF-32 string
 * @param[in]     len    length of the string in dwords
 * @param[in,out] ip    pointer to the index
 * @return                the Unicode character beginning at the index; or
 *                        #EOS if end of input is encountered
 */
utf32_t lb_get_next_char_utf32(
        const utf32_t *s,
        size_t len,
        size_t *ip)
{
    assert(*ip <= len);
    if (*ip == len)
        return EOS;
    return s[(*ip)++];
}

java String 的内部是char[]，char数组，char是16比特，2字节。，某字符，如汉字“中”，UTF-8编码时，字节数组为{-28, -72, -83}。

在java中用String表示则内部char[]为{0x4e2d}，长度为1；而在c中用char[]或char*表示则直接为{-28, -72, -83}，长度为3

        String one = "中";
        int unicodeCodeUnitCount = one.length();//
        String unicodeCodePointValue = Integer.toHexString(one.codePointAt(0));// Unicode编码值
        byte[] storedBytesUtf8 = one.getBytes();// 如果按UTF-8（默认）编码存储需要的字节存储情况
        char char16Bit = one.charAt(0);

        System.out.println("sizeof char = " + Character.SIZE + " (bytes in Java)");
        System.out.println("one.length() = " + unicodeCodeUnitCount + ", one.codePointAt(0) = " + unicodeCodePointValue);
        System.out.println("one.getBytes().length() = " + storedBytesUtf8.length + " : " + bytesToHexString(storedBytesUtf8)
                + ", " + Arrays.toString(storedBytesUtf8));
        System.out.println("one.charAt(0) = " + char16Bit + " = " + Integer.toBinaryString(char16Bit) + " = "
                + Integer.toHexString(char16Bit));
        System.out.println(Character.charCount(char16Bit));

        System.out.println(Integer.toHexString(new String(new byte[] { -28, -72, -83 }).charAt(0)));

        // sizeof char = 16 (bytes in Java)
        // one.length() = 1, one.codePointAt(0) = 4e2d
        // one.getBytes().length() = 3 : e4b8ad, [-28, -72, -83]
        // one.charAt(0) = 中 = 100111000101101 = 4e2d

Unicode符号范围 | UTF-8编码方式（变长编码）
(十六进制) | 字节数| 首字节范围 | 二进制
----------------------+-------+------------+-----------------------------------------------------
0000 0000 - 0000 007F | 单字节 [0x00, 0x7F] 0xxxxxxx
0000 0080 - 0000 07FF | 两字节 [0xC0, 0xE0) 110xxxxx 10xxxxxx
0000 0800 - 0000 FFFF | 三字节 [0xE0, 0xF0) 1110xxxx 10xxxxxx 10xxxxxx
0001 0000 - 001F FFFF | 四字节 [0xF0, 0xF8) 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
0020 0000 - 03FF FFFF | 五字节 [0xF8, 0xFC) 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
0400 0000 - 7FFF FFFF | 六字节 [0xFC, 0xFE) 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

Unicode符号范围	UTF-8编码方式（变长编码）
十六进制	Bytes	首字节范围	二进制
0000 0000 - 0000 007F	单字节	[0x00, 0x7F]	0xxxxxxx
0000 0080 - 0000 07FF	两字节	[0xC0, 0xE0)	110xxxxx 10xxxxxx
0000 0800 - 0000 FFFF	三字节	[0xE0, 0xF0)	1110xxxx 10xxxxxx 10xxxxxx
0001 0000 - 001F FFFF	四字节	[0xF0, 0xF8)	11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
0020 0000 - 03FF FFFF	五字节	[0xF8, 0xFC)	111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
0400 0000 - 7FFF FFFF	六字节	[0xFC, 0xFE)	1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

http://ideone.com/

#include <stdio.h>

typedef unsigned char    utf8_t;        //< Type for UTF-8 data points
typedef unsigned short    utf16_t;    //< Type for UTF-16 data points
typedef unsigned int    utf32_t;    //< Type for UTF-32 data points

#define STRING_TOO_SHORT (-1)        //string too short
#define ILLEGAL_CHARACTER (-2)        //illegal character not starts with 0xxxxxxx, 110xxxxx, 1110xxxx, etc.
#define UNEXPECTED_CHARACTER (-3)    //subsequent characters not of the form 10xxxxxx
//- 4 = character encoded incorrectly(not minimal length).

//   Unicode符号范围    |  UTF-8编码方式（变长编码）
//      (十六进制)      | 字节数| 首字节范围 | 二进制
//----------------------+-------+------------+-----------------------------------------------------
//0000 0000 - 0000 007F | 单字节 [0x00, 0x7F] 0xxxxxxx
//0000 0080 - 0000 07FF | 两字节 [0xC0, 0xE0) 110xxxxx 10xxxxxx
//0000 0800 - 0000 FFFF | 三字节 [0xE0, 0xF0) 1110xxxx 10xxxxxx 10xxxxxx
//0001 0000 - 001F FFFF | 四字节 [0xF0, 0xF8) 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
//0020 0000 - 03FF FFFF | 五字节 [0xF8, 0xFC) 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
//0400 0000 - 7FFF FFFF | 六字节 [0xFC, 0xFE) 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

static inline size_t utf8_seqlen(utf32_t codepoint)
{
    if (codepoint < 0x0000080) return 1;
    if (codepoint < 0x0000800) return 2;
    if (codepoint < 0x0010000) return 3;
    if (codepoint < 0x0200000) return 4;
    if (codepoint < 0x4000000) return 5;
    return 6;
}

static size_t utf8_putc(char *str, size_t len, utf32_t codepoint)
{
    int nbytes = utf8_seqlen(codepoint);
    if (!str)
        return nbytes;
    if (len < nbytes)
        return -1;

    // This is easier done backwards
    int b = nbytes;
    while (b > 1) {
        b--;
        str[b] = 0x80 | (codepoint & 0x3f);
        codepoint >>= 6;
    }

    switch (nbytes) {
    case 1: str[0] = (codepoint & 0x7f); break;
    case 2: str[0] = 0xc0 | (codepoint & 0x1f); break;
    case 3: str[0] = 0xe0 | (codepoint & 0x0f); break;
    case 4: str[0] = 0xf0 | (codepoint & 0x07); break;
    case 5: str[0] = 0xf8 | (codepoint & 0x03); break;
    case 6: str[0] = 0xfc | (codepoint & 0x01); break;
    }

    return nbytes;
}

//static unsigned char utf8_b0masks[] = { 0x1f, 0x0f, 0x07, 0x03, 0x01};
//#define utf8_extra_first_byte(nbytes) utf8_b0masks[nbytes - 2]

//It returns the number of characters read or a negative error code
static size_t utf8_getc(const utf8_t *str, size_t len, utf32_t  *cp)
{
    unsigned char b0 = (str++)[0], b0mask;
    int nbytes;//UTF-8编码下一个字符占有多少字节

    if (b0 < 0x80) { // ASCII
        //nbytes = 1;
        if (len >= 1){
            *cp = b0; return 1;
        }
        return STRING_TOO_SHORT;
    }else if (b0 < 0xc0){ // C1 or continuation
        return ILLEGAL_CHARACTER;
    }else if (b0 < 0xe0) {
        nbytes = 2; b0mask = 0x1f;
    }else if (b0 < 0xf0) {
        nbytes = 3; b0mask = 0x0f;
    }else if (b0 < 0xf8) {
        nbytes = 4; b0mask = 0x07;
    }else if (b0 < 0xfc){
        nbytes = 5; b0mask = 0x03;
    }else if (b0 < 0xfe){
        nbytes = 6; b0mask = 0x01;
    }else
        return ILLEGAL_CHARACTER;

    if (len < nbytes)
        return STRING_TOO_SHORT;

    *cp = b0 & b0mask;
    for (int i = 1; i < nbytes; i++) {
        b0 = (str++)[0];
        if ((b0 & 0xc0) != 0x80) 
            return UNEXPECTED_CHARACTER;
        *cp <<= 6;
        *cp |= b0 & 0x3f;
    }

    return nbytes;
}


int main(void) {
    // your code goes here
    utf32_t cp;
    size_t seqlen = utf8_getc("22", 2, &cp);
    printf("%d, %d", seqlen, cp);
    return 0;
}

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