Use php to verify whether a string is a number

It is very easy to use regular expressions to verify whether a string is a number in php. The most important thing is how to write regular expressions and master regular expressions. As for how to write expressions, here we use regular expressions to list ways to judge numbers.

The first method:

Use the function is_numeric() to verify

bool is_numeric ( mixed $var )

• $var: Variable to be detected

• Return value: TRUE if the specified variable is a number or numeric string, otherwise it returns FALSE, pay attention to floating point Type returns a null value, which is FALSE.

if(is_numeric($str)) echo('是数字'); else echo('不是数字');

Second method:

Use regular expression verification

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