How to determine whether two strings are equal in php

The methods for determining string equality in PHP include: 1. Strict equality operator (===) compares content and type; 2. Loose equality operator (==) compares content and tolerates type differences; 3. . The strcmp() function performs character comparison and returns an integer to represent the result; 4. The mb_strcmp() function supports multi-byte string comparison; 5. The hash_equals() function safely compares hash strings.

How to determine whether two strings are equal in PHP

In PHP, determine whether two strings are equal Commonly used methods for equality are as follows:

1. Strict equality operator (===)

The most strict equality comparison method requires the sum of the two string contents. The types are all the same.

$string1 = "Hello World";
$string2 = "Hello World";

// 使用 === 严格相等运算符
if ($string1 === $string2) {
    echo "两个字符串相等";
}

2. Loose equality operator (==)

Allows many forms of equality comparison, including strings with the same content but different types.

$string1 = "5";
$string2 = 5;

// 使用 == 松散相等运算符
if ($string1 == $string2) {
    echo "两个字符串相等";
}

3. strcmp() function

Compares the characters of two strings and returns an integer:

• 0: Two Strings are equal
• Positive number: the first string is greater than the second string
• Negative number: the first string is less than the second string

$result = strcmp("Hello", "World");
// 结果为 -1，表示 "Hello" 小于 "World"

4. mb_strcmp() function

is similar to strcmp(), but supports multi-byte string comparison.

$string1 = "你好";
$string2 = "世界";

$result = mb_strcmp($string1, $string2);
// 结果为 0，表示两个字符串相等

5. hash_equals() function

Safely compares two hash strings to prevent timing attacks.

$hash1 = hash("sha256", "密码");
$hash2 = hash("sha256", "密码");

if (hash_equals($hash1, $hash2)) {
    echo "两个哈希值相等";
}

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