为什么字符串大于或小于整数？

Question

I am not able to get it that why the statement gets true both the times.?

$hello="foo";
     if($hello<=6){
        echo "yes
";
     }
     if ($hello>=0) {
        echo "ohh yess!";
     }

it outputs

yes
ohh yess!

I do know this is illegal comparison between integer and string,but why after all it gets true.

Answer 1

As the PHP manual says:

The value is given by the initial portion of the string. If the string starts with valid numeric data, this will be the value used. Otherwise, the value will be 0 (zero).

In this case, the string foo evaluates to zero when the comparison is done and both the if conditions will hence evaluate to TRUE.

Effectively, you'll be doing:

if(0 <= 6) {
    echo "yes
";
}

if (0 >= 0) {
    echo "ohh yess!";
}

Use === operator if you want to make sure the variable types are also taken into consideration.