[php] 문자 출력하는 방법 echo print_r printf var_dump

1. var_dump, print_r, printf, var_dump

<?php

echo "var_dump\n";
var_dump("aaa");

echo "print_r\n";
print_r("aaa\n");

echo "echo\n";
echo "aaa\n";

echo "printf\n";
printf("aaa\n");
?>