php 判断字符串相等

<?php
$str1 = "Hello";
$str2 = "Hello";
$str3 = "hello";

// 使用 == 运算符
if ($str1 == $str2) {
    echo "str1 and str2 are equal (using ==)";
} else {
    echo "str1 and str2 are not equal (using ==)";
}

if ($str1 == $str3) {
    echo "str1 and str3 are equal (using ==)";
} else {
    echo "str1 and str3 are not equal (using ==)";
}

// 使用 === 运算符
if ($str1 === $str2) {
    echo "str1 and str2 are equal (using ===)";
} else {
    echo "str1 and str2 are not equal (using ===)";
}

if ($str1 === $str3) {
    echo "str1 and str3 are equal (using ===)";
} else {
    echo "str1 and str3 are not equal (using ===)";
}
?>

str1 and str2 are equal (using ==)
str1 and str3 are not equal (using ==)
str1 and str2 are equal (using ===)
str1 and str3 are not equal (using ===)