In PHP, is there any difference between the != and <> operators?
在PHP中，！=和<>运算符之间有什么区别吗？
In the manual, it states:
在手册中，它指出：
$a != $b Not equal TRUE if $a is not equal to $b after type juggling.
$a <> $b Not equal TRUE if $a is not equal to $b after type juggling.
I guess there are no huge differences but I'm curious.
我想没有太大的差异，但我很好奇。
6 个解决方案
#1
58
In the main Zend implementation there is not any difference. You can get it from the Flex description of the PHP language scanner:
在主要的Zend实现中没有任何区别。您可以从PHP语言扫描程序的Flex描述中获取它：
<ST_IN_SCRIPTING>"!="|"<>" {
return T_IS_NOT_EQUAL;
}
Where T_IS_NOT_EQUAL is the generated token. So the Bison parser does not distinguish between <> and != tokens and treats them equally:
其中T_IS_NOT_EQUAL是生成的令牌。所以Bison解析器不区分<>和！= tokens并平等对待它们：
%nonassoc T_IS_EQUAL T_IS_NOT_EQUAL T_IS_IDENTICAL T_IS_NOT_IDENTICAL
%nonassoc '<' T_IS_SMALLER_OR_EQUAL '>' T_IS_GREATER_OR_EQUAL
#2
22
As the accepted answer points out the implementation is identical, however there is a subtle difference between them in the documentation...
正如接受的答案所指出的那样，实现是相同的，但是文档中它们之间存在细微差别......
According to this page the <> operator has slightly higher precedence than !=.
根据此页面，<>运算符的优先级略高于！=。
I'm not sure if this is a bug in the Zend implementation, a bug in the documentation, or just one of those cases where PHP decides to ignore the precedence rules.
我不确定这是Zend实现中的错误，文档中的错误，还是PHP决定忽略优先规则的情况之一。
Update: The documentation is updated and there is no longer any difference between <> and !=.
更新：文档已更新，<>和！=之间不再有任何区别。
#3
8
They are the same. However there are also !== and === operators which test for exact equality, defined by value and type.
他们是一样的。但是也有！==和===运算符测试由值和类型定义的精确相等。
#4
5
<> means either bigger or smaller. != means not equal. They basically mean the same thing.
<>表示更大或更小。 ！=表示不相等。它们基本上意味着同样的事情。
#5
4
As everyone is saying they are identical, one from one language branch C-style/shell, one from some others including MySQL which was highly integrated in the past.
正如每个人都说他们是相同的，一个来自一个语言分支C风格/ shell，一个来自其他一些包括MySQL，过去高度集成。
<> should be considered syntactic sugar, a synonym for != which is the proper PHP style for not-equal.
<>应该被认为是语法糖，是！=的同义词，这是不正确的PHP风格。
Further emphasised by the triple character identity function !==.
三重字符识别功能进一步强调了！==。
#6
1
<> is exactly the same as != operator since both of them are parsed as T_IS_NOT_EQUAL token.
<>与！=运算符完全相同，因为它们都被解析为T_IS_NOT_EQUAL标记。
And they have same precedence.
他们有同样的优先权。
#1
58
In the main Zend implementation there is not any difference. You can get it from the Flex description of the PHP language scanner:
在主要的Zend实现中没有任何区别。您可以从PHP语言扫描程序的Flex描述中获取它：
<ST_IN_SCRIPTING>"!="|"<>" {
return T_IS_NOT_EQUAL;
}
Where T_IS_NOT_EQUAL is the generated token. So the Bison parser does not distinguish between <> and != tokens and treats them equally:
其中T_IS_NOT_EQUAL是生成的令牌。所以Bison解析器不区分<>和！= tokens并平等对待它们：
%nonassoc T_IS_EQUAL T_IS_NOT_EQUAL T_IS_IDENTICAL T_IS_NOT_IDENTICAL
%nonassoc '<' T_IS_SMALLER_OR_EQUAL '>' T_IS_GREATER_OR_EQUAL
#2
22
As the accepted answer points out the implementation is identical, however there is a subtle difference between them in the documentation...
正如接受的答案所指出的那样，实现是相同的，但是文档中它们之间存在细微差别......
According to this page the <> operator has slightly higher precedence than !=.
根据此页面，<>运算符的优先级略高于！=。
I'm not sure if this is a bug in the Zend implementation, a bug in the documentation, or just one of those cases where PHP decides to ignore the precedence rules.
我不确定这是Zend实现中的错误，文档中的错误，还是PHP决定忽略优先规则的情况之一。
Update: The documentation is updated and there is no longer any difference between <> and !=.
更新：文档已更新，<>和！=之间不再有任何区别。
#3
8
They are the same. However there are also !== and === operators which test for exact equality, defined by value and type.
他们是一样的。但是也有！==和===运算符测试由值和类型定义的精确相等。
#4
5
<> means either bigger or smaller. != means not equal. They basically mean the same thing.
<>表示更大或更小。 ！=表示不相等。它们基本上意味着同样的事情。
#5
4
As everyone is saying they are identical, one from one language branch C-style/shell, one from some others including MySQL which was highly integrated in the past.
正如每个人都说他们是相同的，一个来自一个语言分支C风格/ shell，一个来自其他一些包括MySQL，过去高度集成。
<> should be considered syntactic sugar, a synonym for != which is the proper PHP style for not-equal.
<>应该被认为是语法糖，是！=的同义词，这是不正确的PHP风格。
Further emphasised by the triple character identity function !==.
三重字符识别功能进一步强调了！==。
#6
1
<> is exactly the same as != operator since both of them are parsed as T_IS_NOT_EQUAL token.
<>与！=运算符完全相同，因为它们都被解析为T_IS_NOT_EQUAL标记。
And they have same precedence.
他们有同样的优先权。