How to determine whether two strings are equal (equal) in PHP

Judgment method: 1. Use the "===" operator, the syntax "String 1=== String 2"; 2. Use the strcmp() function, the syntax "strcmp(String 1,Character String 2)"; 3. Use the strcasecmp() function, the syntax is "strcasecmp(String 1, String 2)".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Determine characters in php String equality is not equal (equal)

Method 1: Use the "===" operator

"===" is congruent Operator that returns TRUE if $a and $b are not only equal in value but also equal in type, otherwise it returns FALSE.

<?php
header("Content-type:text/html;charset=utf-8");
$pwd1 = &#39;password&#39;;
$pwd2 = &#39;Password&#39;;
if($pwd1===$pwd2){
    echo &#39;密码不匹配！&#39;;
} else {
    echo &#39;密码匹配！&#39;;
}
?>

Method 2: Use strcmp() function

strcmp() function can perform binary security on two strings Comparison is case-sensitive and its syntax is as follows:

strcmp(string $str1, string $str2)

where $str1 and $str2 are the two strings to be compared.

The strcmp() function will return different values ​​according to the comparison result. If $str1 is less than $str2, the return value is < 0; if $str1 is greater than $str2, the return value is > 0; if $str1 If equal to $str2, 0 is returned.

When we register an account on a website, the user password usually needs to be entered twice to confirm, in order to reduce password setting errors caused by input errors. Because passwords are usually case-sensitive, you can use the strcmp() function to compare the passwords entered twice. The sample code is as follows:

<?php
header("Content-type:text/html;charset=utf-8");
$pwd1 = &#39;password&#39;;
$pwd2 = &#39;Password&#39;;
if(strcmp($pwd1, $pwd2) != 0){
    echo &#39;密码不匹配！&#39;;
} else {
    echo &#39;密码匹配！&#39;;
}
?>

Note that for strcmp () function, the two strings to be compared must match exactly to be considered equal. For example, $pwd1 and $pwd2 in the example code are different. If you want to compare two strings in a case-insensitive manner, you can use the strcasecmp() function.

Method 3: Use the strcasecmp() function

The strcasecmp() function in PHP has similar functions to the strcmp() function, both of which can compare two strings. The difference is that the strcasecmp() function is not case-sensitive when comparing strings. Its syntax format is as follows:

strcasecmp(string $str1, string $str2)

Among them, $str1 and $str2 are the two strings to be compared.

According to the comparison result, if $str1 is less than $str2, the return value is < 0; if $str1 is greater than $str2, the return value is > 0; if $str1 is equal to $str2, then 0 is returned.

Website URLs are not case-sensitive, so we can use the strcasecmp() function to compare whether two URLs are the same. The sample code is as follows:

<?php
header("Content-type:text/html;charset=utf-8");
$url1 = &#39;http://www.php.cn/&#39;;
$url2 = &#39;HTTP://www.php.cn/&#39;;
if(strcasecmp($url1, $url2) == 0){
    echo &#39;两个网址相同&#39;;
} else {
    echo &#39;两个网址不同&#39;;
}
?>

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