How to remove the first digits of the first line of a string in php

In the development process of PHP, we often encounter situations where we need to remove the first few characters of the first line of a string. This is a relatively common operation. Several commonly used methods will be introduced below.

1. Use the substr() function

The substr() function is a function used to intercept strings in PHP. You can specify the beginning of the intercepted string. location and length. Therefore, we can use the substr() function to remove the first few digits of the first line of the string.

The following is the code that uses the substr() function to remove the first 3 digits of the first line of a string:

$originalStr = "Hello world! \nI am a PHP developer.";
$cutStr = substr($originalStr, 4);
echo $cutStr;

Among them, $originalStr is the original string, and $cutStr is to remove the first 3 digits of the first line. The string after the bit. Multi-line strings can be represented by using newline characters \n to separate strings.

2. Use the explode() and implode() functions

The explode() function splits the string according to a certain delimiter and returns an array. The implode() function concatenates an array with a specific character and returns a string. We can use these two functions to remove the first few digits of the first line of a string.

The following is the code that uses the explode() and implode() functions to remove the first 3 digits of the first line of the string:

$originalStr = "Hello world! \nI am a PHP developer.";
$lineArr = explode("\n", $originalStr);
$lineArr[0] = substr($lineArr[0], 3);
$cutStr = implode("\n", $lineArr);
echo $cutStr;

Among them, $originalStr is the original string, and $cutStr is to remove the first 3 digits of the string. The string after the first 3 digits of a line. $lineArr is a string array separated by \n. Use array subscripts to modify the first few characters of the first line, and finally use the implode() function to convert the array into a new string.

3. Use the preg_replace() function

The preg_replace() function is a function used for regular expression replacement in PHP. It can replace certain characters in a string. Partially replaced with specified content. We can use the preg_replace() function to remove the first few characters of the first line of the string.

The following is the code to use the preg_replace() function to remove the first 3 digits of the first line of the string:

$originalStr = "Hello world! \nI am a PHP developer.";
$cutStr = preg_replace('/^[^\n]{3}/', '', $originalStr);
echo $cutStr;

Among them, $originalStr is the original string, and $cutStr is to remove the first 3 digits of the first line. The string after the bit. The regular expression '/^¹{3}/' represents the first three lines ending with a newline character \n. Use the preg_replace() function to replace this part with nothing, that is, remove the first few digits.

Summary:

To remove the first digits of the first line of a string in PHP, you can use the substr() function, explode() and implode() functions, and preg_replace () function and many other methods. These methods can all achieve the same effect, but using different methods will affect the performance and readability of the code. In actual development, you should choose the method that best suits you.

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