php how to check whether a string contain only numers code example

Example 1: check if includes numbers php

if (preg_match('~[0-9]+~', $string)) {
    echo 'string with numbers';
}

Example 2: php check if string contains number

if (preg_match('/[A-Za-z]/', $myString) && preg_match('/[0-9]/', $myString))
{
    echo 'Contains at least one letter and one number';
}