在PHP中，可以使用双等号（==）或三个等号（===）来判断两个字符串是否相等。
$str1 = "Hello";
$str2 = "hello";
if ($str1 == $str2) {
echo "Strings are equal";
} else {
echo "Strings are not equal";
}
$str1 = "Hello";
$str2 = "hello";
if ($str1 === $str2) {
echo "Strings are equal";
} else {
echo "Strings are not equal";
}
