Home>Article>Backend Development> PHP function that compares the first n characters (case-insensitive) of two strings
Example
Compare twostrings(not case sensitive):
Definition and usage
strncasecmp() function compares two string (case-insensitive).
Note: strncasecmp() is binary safe and case-insensitive.
Tips: This function is similar to thestrcasecmp() function, except that strcasecmp() has no length parameter.
Syntax
strncasecmp(string1,string2,length)
| Parameters | Description |
| string1 | Required. Specifies the first string to compare. |
| string2 | Required. Specifies the second string to be compared. |
| length | Required. Specifies the number of characters per string used for comparison. |
Technical details
更多实例
实例 1
比较两个字符串（不区分大小写，Hello 和 hELLo 输出相同）：
"; echo strncasecmp("Hello","hELLo",6); ?>
只是这样就需要转换两次。大多时候，我们是针对字符集转换的时候才会这样，比如判断参数传进来是否utf-8，这5个字符的写法，可就多了，比如UTF-8，Utf-8,utf-8等，那我们怎么办呢？strtolower?strupper?不需要啦。。
strncasecmp($a,$b,$length)就可以了。。
如果返回是0则相等，那我们怎么判断呢？
strncasecmp($str,'utf-8',5) == 0那么，传入的参数就是utf8的，是否很方便呢？
只是这些函数我们平时不太用得到，我看到这个函数的用法却是在 yii framework，他在处理事件的时候，判断前两个字符是否为 on 的时候，就是这样判断的。我也因此学到了一招。
strncasecmp Definition and Usage
定义和用法
The strncasecmp() function compares two strings.
strncasecmp()函数的作用是：比较字符串的前n个字符（大小写不敏感）。
| Return value: | This function returns:
|
| 4.0.2+ |
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