PHP determines whether it is a number

PHP is_numeric Detects whether a variable is a number or a numeric string (Recommended learning: PHP Programming from Beginner to Master)

bool is_numeric ( mixed $var )

Returns TRUE if var is a number or numeric string, otherwise returns FALSE.

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For example 1:

The above script will output:

bool(true)

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For example 2:

boolean true
//
function int_str($str){
    if(is_numeric($str)){
        $str = 'm'.$str;
    }
    return $str;
}

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