How to query items containing specific characters in PHP (4 ways)

PHP is a popular server-side scripting language. In web development, it is often necessary to query for items containing a specific string. This article will introduce how to query methods containing strings in PHP.

1. strstr() function

strstr() function is used to find another string in a string and return the substring from that string to the end of the string. string. If not found, returns false. The syntax of this function is as follows:

strstr(string $haystack , mixed $needle [, bool $before_needle = false ] ) : string|false

Among them, $haystack represents the string to be searched, $needle represents the string to be found, and $before_needle represents whether to truncate the substring to $needle.

For example, to search whether the string "abcdef" contains "cd", the code is as follows:

if (strstr("abcdef", "cd")) {
    echo "字符串中包含'cd'";
} else {
    echo "字符串中不包含'cd'";
}

This code will output "the string contains 'cd'". The sample code illustrates how to use the strstr() function to find a string in PHP.

2. strpos() function

The strpos() function is used to find the first occurrence of a substring in a string and return it as an integer. If not found, returns false. The syntax of this function is as follows:

strpos(string $haystack , mixed $needle [, int $offset = 0 ] ) : int|false

Among them, $haystack represents the string to be searched, $needle represents the string to be found, and $offset represents the position to start the search.

For example, to search whether the string "abcdef" contains "cd", the code is as follows:

if (strpos("abcdef", "cd") !== false) {
    echo "字符串中包含'cd'，位置为：" . strpos("abcdef", "cd");
} else {
    echo "字符串中不包含'cd'";
}

This code will output "The string contains 'cd', position: 2" . The sample code illustrates how to use the strpos() function to find a string in PHP.

3. preg_match() function

The preg_match() function is used to perform a regular expression match in a string and return whether a match is found. If not found, returns 0; otherwise returns 1. The syntax of this function is as follows:

preg_match(string $pattern , string $subject [, array &$matches [, int $flags = 0 [, int $offset = 0 ]]] ) : int|false

Among them, $pattern is a regular expression, $subject represents the string to be matched, $matches represents saving the matching results (optional), and $flags represents the matching flag ( Optional), $offset indicates the starting position of matching (optional).

For example, to search whether the string "abcdef" contains "c or d", the code is as follows:

if (preg_match("/[cd]/", "abcdef")) {
    echo "字符串中包含'c'或'd'";
} else {
    echo "字符串中不包含'c'或'd'";
}

This code will output "The string contains 'c' or 'd' ". The sample code illustrates how to use the preg_match() function to find a string in PHP.

4. stripos() function

stripos() function is used to find the first occurrence of a substring in a string and return it as an integer. Unlike the strpos() function, it is not case sensitive. If not found, returns false. The syntax of this function is as follows:

stripos(string $haystack , mixed $needle [, int $offset = 0 ] ) : int|false

The remaining parameters are the same as the strpos() function.

For example, to search whether the string "abcdef" contains "CD", the code is as follows:

if (stripos("abcdef", "CD") !== false) {
    echo "字符串中包含'CD'，位置为：" . stripos("abcdef", "CD");
} else {
    echo "字符串中不包含'CD'";
}

This code will output "The string contains 'CD', position: 2" . The sample code illustrates how to use the stripos() function to find a string in PHP.

Summary

As a popular server-side scripting language, PHP's built-in functions provide many convenient methods to manipulate strings. Whether it's the strstr() function, strpos() function, preg_match() function, or stripos() function, there are different ways to find items that contain strings. Developers can choose appropriate functions to process string queries based on their needs.

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