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if(0=='0') {echo "0=='0'"; }if(0=='') {echo "0==''"; }if('0'=='') {echo "'0'==''"; }
输出0=='0'0==''为什么最后一个不相等呢？
Solve the problem of php string ==? -PHP Chinese website Q&A-How to solve the problem of php string ==? -PHP Chinese website Q&A
Let’s take a look and learn.
这三个if判断，前两个是数值比较，最后一个是字符串比较；
前两个数值比较，会将字符串转换成数字
按照规则：如果字符串以合法的数字数据开始，就用该数字作为其值，否则其值为 0（零）；
最后的字符串比较，就是单纯的字符串之间判断是否相同；
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
Solve the problem of php string ==? -PHP Chinese website Q&A-How to solve the problem of php string ==? -PHP Chinese website Q&A
Let’s take a look and learn.
这三个if判断，前两个是数值比较，最后一个是字符串比较；
前两个数值比较，会将字符串转换成数字
按照规则：如果字符串以合法的数字数据开始，就用该数字作为其值，否则其值为 0（零）；
最后的字符串比较，就是单纯的字符串之间判断是否相同；