Find the position of another string in a string using PHP function 'strpos'

Use the PHP function "strpos" to find the position of another string in a string

In PHP, we often need to find the position of another string in a string. This is very common when working with text, search and replace, etc. PHP provides many string processing functions, one of which is very useful function is "strpos", which can help us quickly find the position of the target string in the source string.

The following is a simple code example that demonstrates how to use the "strpos" function to find the position of a string within another string:

<?php
$sourceString = "Hello, world! This is a test string.";
$targetString = "world";

$position = strpos($sourceString, $targetString);

if ($position !== false) {
    echo "目标字符串 '" . $targetString . "' 在源字符串中的位置是：" . $position;
} else {
    echo "目标字符串 '" . $targetString . "' 未在源字符串中找到。";
}
?>

In the above example, we first define A source string and a target string. We then use the "strpos" function to find the position of the target string within the source string. If the target string exists in the source string, the "strpos" function returns the index of the first character of the target string in the source string, otherwise it returns false.

Next, we use a conditional statement to determine the return value of the "strpos" function. If the return value is not false, then we print out the position of the target string in the source string. Otherwise, we print out the message that the target string is not found in the source string.

Assuming we run the above code example, the output will be:

The position of the target string 'world' in the source string is: 7

In this example , the position of the target string "world" in the source string "Hello, world! This is a test string." is the position with index value 7.

It should be noted that if the position of the target string in the source string is 0, then the "strpos" function will return 0, which is also a valid position. Therefore, we cannot simply use the following code to determine whether the target string is found in the source string:

if (strpos($sourceString, $targetString)) {
    // 目标字符串在源字符串中找到
}

Since the "strpos" function returns a Boolean value of false when the target string is not found, the above The conditional statement will not be able to accurately determine whether the target string is found in the source string. The correct approach should be to use the congruence operator to determine whether the return value is not equal to false, as shown below:

if (strpos($sourceString, $targetString) !== false) {
    // 目标字符串在源字符串中找到
}

To summarize, PHP's "strpos" function is a very useful function that can help us in Find the position of another string within a string. By using this function properly, we can handle string-related operations more efficiently. I hope the examples and explanations in this article will be helpful to you.

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