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Home Backend Development PHP Tutorial php中字符串判断疑问

php中字符串判断疑问

Jun 23, 2016 pm 01:38 PM

如下:为何返回为true?
if(0 == 'name'){
echo true;
}else{
echo false;
}

把0换做其他数字则返回为false
if(1== 'name'){
echo true;
}else{
echo false;
}


回复讨论(解决方案)

这个是Php的一个解析机制问题,
if(1 == '1name'){
echo true;
}else{
echo false;
}

这样就是true

貌似是 
拿字符串和数字来比较,会把字符串给转成数字(转为0),所以相等
和1比较就不等了

数字与字符串比较时, 先尝试将字符串转换为数字, 再比较, 一个不能转换为数字的字符串, 转换结果为0

字符串与数字相比较时,字符串会转换成数字参与比较。‘name’ 转化成数字是0 ,所以就相等了。

当字符串和资源与数字像比较时, 将字符串和资源转换成数字,按普通数学比较

php会自动转换被比较的类型! 
你前面是0整型  后面是 ‘name’字符串   php会将字符串转换成数字 但name无法转换成数字 所以只能返回0 0=0 !
如果你比较的是0和‘123’ 那就不相等了!

var_dump((int)'123');var_dump((int)'name');
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