VC正则表达式的使用
2010年9月11日星期六 邵盛松
正则表达式是一种对字符进行模糊匹配的一个公式。在数据有效性验证,查找,替换文本中都可以使用正则表达式 。
本篇文章主要描述的是使用ATL中两个模板类CAtlRegExp和CAtlREMatchContext。
在使用CAtlRegExp类之前需要添加#include <atlrx.h> 这个头文件。
RegExp是Regular Expression的缩写
以匹配邮件地址字符串为例说明两个类的使用
该示例更改自http://msdn.microsoft.com/en-us/library/k3zs4axe(VS.80).aspx
CString strRegex=L"({[0-9_]+@[a-zA-Z0-9]+[.][a-zA-Z0-9]+[.]?[a-zA-Z0-9]+})";
CString strInput;
strInput=L"admin@domain.com";
CAtlRegExp<CAtlRECharTraitsW> reRule;
wchar_t *wt = (wchar_t *)(LPCTSTR)strRegex;
REParseError status = reRule.Parse((const ATL::CAtlRegExp<CAtlRECharTraitsW>::RECHAR *)wt);
if (REPARSE_ERROR_OK != status)
{
return 0;
}
CAtlREMatchContext<CAtlRECharTraitsW> mcRule;
wt = (wchar_t *)(LPCTSTR)strInput;
if (!reRule.Match((const ATL::CAtlRegExp<CAtlRECharTraitsW>::RECHAR *)wt,&mcRule))
{
AfxMessageBox(L"您输入的邮件地址不合法!");
}
else
{
for (UINT nGroupIndex = 0; nGroupIndex < mcRule.m_uNumGroups; ++nGroupIndex)
{
const CAtlREMatchContext<>::RECHAR* szStart = 0;
const CAtlREMatchContext<>::RECHAR* szEnd = 0;
mcRule.GetMatch(nGroupIndex, &szStart, &szEnd);
ptrdiff_t nLength = szEnd - szStart;
CString strEmailAddress(szStart, static_cast<int>(nLength));
if(strEmailAddress.Compare(strInput)!=0)
{
CString strPrompt;
strPrompt.Format(L"您输入的邮件地址不合法,您要输入%s 吗!",strEmailAddress);
AfxMessageBox(strPrompt);
}
else
{
AfxMessageBox(L"输入的邮件地址正确!");
}
}
}
这两个模板类由另一个描述字符集特性的类参数化,可以是ASCII,WCHAR 或多字节。
可以将此忽略掉,因为根据设置的字符集,模板类自动生成具体的类。
在atlrx.h文件*选择的有三个类
CAtlRECharTraitsA 用于ASCII
CAtlRECharTraitsW 用于UNICODE
CAtlRECharTraitsMB 用于多字节
在VC2005默认的字符集是使用Unicode字符集
根据正则的源码
#ifndef _UNICODE
typedef CAtlRECharTraitsA CAtlRECharTraits;
#else // _UNICODE
typedef CAtlRECharTraitsW CAtlRECharTraits;
#endif // !_UNICODE
所以构造CAtlRegExp类可以是
CAtlRegExp<> reRule;
REParseError status = reRule.Parse((const ATL::CAtlRegExp<CAtlRECharTraitsW>::RECHAR *)wt);
也可以是
CAtlRegExp<CAtlRECharTraitsW> reRule;
REParseError status = reRule.Parse((const ATL::CAtlRegExp<CAtlRECharTraitsW>::RECHAR *)wt);
通过调用CAtlRegExp的Parse()方法,使用正则表达式字符串作为参数,就可以构造出一个我们所需要的类。
调用CATLRegExp的Match()函数
Match()函数参数说明
第一个参数是要对比的字符串,
第二个参数是存储match的结果
CAtlREMatchContext的成员变量m_uNumGroups表示匹配的Group
CAtlREMatchContext的GetMatch()函数返回匹配上的字符串的pStart和pEnd指针
以下从MSDN摘录的正则表达语法
原文是http://msdn.microsoft.com/en-us/library/k3zs4axe(VS.80).aspx
Regular Expression Syntax
This table lists the metacharacters understood by CAtlRegExp.
Metacharacter |
Meaning |
. |
Matches any single character. |
[ ] |
Indicates a character class. Matches any character inside the brackets (for example, [abc] matches "a", "b", and "c"). |
^ |
If this metacharacter occurs at the start of a character class, it negates the character class. A negated character class matches any character except those inside the brackets (for example, [^abc] matches all characters except "a", "b", and "c"). If ^ is at the beginning of the regular expression, it matches the beginning of the input (for example, ^[abc] will only match input that begins with "a", "b", or "c"). |
- |
In a character class, indicates a range of characters (for example, [0-9] matches any of the digits "0" through "9"). |
? |
Indicates that the preceding expression is optional: it matches once or not at all (for example, [0-9][0-9]? matches "2" and "12"). |
+ |
Indicates that the preceding expression matches one or more times (for example, [0-9]+ matches "1", "13", "456", and so on). |
* |
Indicates that the preceding expression matches zero or more times. |
??, +?, *? |
Non-greedy versions of ?, +, and *. These match as little as possible, unlike the greedy versions that match as much as possible (for example, given the input "<abc><def>", <.*?> matches "<abc>" while <.*> matches "<abc><def>"). |
( ) |
Grouping operator. Example: (/d+,)*/d+ matches a list of numbers separated by commas (for example, "1" or "1,23,456"). |
{ } |
Indicates a match group. The actual text in the input that matches the expression inside the braces can be retrieved through the CAtlREMatchContext object. |
/ |
Escape character: interpret the next character literally (for example, [0-9]+ matches one or more digits, but [0-9]/+ matches a digit followed by a plus character). Also used for abbreviations (such as /a for any alphanumeric character; see the following table). If / is followed by a number n, it matches the nth match group (starting from 0). Example: <{.*?}>.*?<//0> matches "<head>Contents</head>". Note that, in C++ string literals, two backslashes must be used: "//+", "//a", "<{.*?}>.*?<///0>". |
$ |
At the end of a regular expression, this character matches the end of the input (for example,[0-9]$ matches a digit at the end of the input). |
| |
Alternation operator: separates two expressions, exactly one of which matches (for example, T|the matches "The" or "the"). |
! |
Negation operator: the expression following ! does not match the input (for example, a!b matches "a" not followed by "b"). |
Abbreviations
CAtlRegExp can handle abbreviations, such as /d instead of [0-9]. The abbreviations are provided by the character traits class passed in the CharTraits parameter. The predefined character traits classes provide the following abbreviations.
Abbreviation |
Matches |
/a |
Any alphanumeric character: ([a-zA-Z0-9]) |
/b |
White space (blank): ([ //t]) |
/c |
Any alphabetic character: ([a-zA-Z]) |
/d |
Any decimal digit: ([0-9]) |
/h |
Any hexadecimal digit: ([0-9a-fA-F]) |
/n |
Newline: (/r|(/r?/n)) |
/q |
A quoted string: (/"[^/"]*/")|(/'[^/']*/') |
/w |
A simple word: ([a-zA-Z]+) |
/z |
An integer: ([0-9]+) |
关于语法翻译可参考http://www.vckbase.com/document/viewdoc/?id=1138
摘录
字符元 |
意义 |
. |
匹配单个字符 |
[ ] |
指定一个字符类,匹配方括号内的任意字符。例:[abc] 匹配 "a", "b"或 "c"。 |
^ |
如果^出现在字符类的开始处,它否定了字符类,这个被否定的字符类匹配除却方括号内的字符的字符。如:[^abc]匹配除了"a", "b"和"c"之外的字符。如果^出现在正则表达式前边,它匹配输入的开头,例:^[abc]匹配以"a", "b"或"c"开头的输入。 |
- |
在字符类中,指定一个字符的范围。例如:[0-9]匹配"0"到"9"的数字。 |
? |
指明?前的表达式是可选的,它可以匹配一次或不进行匹配。例如: [0-9][0-9]? 匹配"2"或"12"。 |
+ |
指明?前的表达式匹配一次或多次。例如:[0-9]+匹配"1", "13", "666"等。 |
* |
指明*前的表达式匹配零次或多次。 |
??, +?, *? |
?, +和*的非贪婪匹配版本,它们尽可能匹配较少的字符;而?, +和*则是贪婪版本,尽可能匹配较多的字符。例如:输入"<abc><def>", 则<.*?> 匹配"<abc>",而<.*>匹配"<abc><def>"。 |
( ) |
分组操作符。例如:(/d+,)*/d+匹配一串由逗号分开的数字,例如: "1"或"1,23,456"。 |
/ |
转义字符,转义紧跟的字符。例如,[0-9]+ 匹配一个或多个数字,而 [0-9]/+ 匹配一个数字后跟随一个加号的情况。反斜杠/也用于表示缩写,/a 就表示任何数字、字母。如果/后紧跟一个数字n,则它匹配第n个匹配群组(从0开始),例如,<{.*?}>.*?<//0>匹配"<head>Contents</head>"。注意,在C++字符串中,反斜杠/需要用双反斜杠//来表示: "//+", "//a", "<{.*?}>.*?<///0>"。 |
$ |
放在正则表达式的最后,它匹配输入的末端。例如:[0-9]$匹配输入的最后一个数字。 |
| |
间隔符,分隔两个表达式,以正确匹配其中一个,例如:T|the匹配"The" 或"the"。 |
缩写匹配
缩写 |
匹配 |
/a |
字母、数字([a-zA-Z0-9]) |
/b |
空格(blank): ([ //t]) |
/c |
字母([a-zA-Z]) |
/d |
十进制数 ([0-9]) |
/h |
十六进制数([0-9a-fA-F]) |
/n |
换行: (/r|(/r?/n)) |
/q |
引用字符串(/"[^/"]*/")|(/''''[^/'''']*/'''') |
/w |
一段文字 ([a-zA-Z]+) |
/z |
一个整数([0-9]+) |
以上程序在VC++2005 unicode字符集下调试通过
本文完