The substr function intercepts part of the string in php (with detailed explanation)

The substr function intercepts part of the string in PHP (with detailed explanation)

I often see novices asking about PHP Is there any left function or right function similar to asp, which can be used to intercept N characters starting from the left or right side of a string? The answer is of course yes. The substr function in PHP can do this, but PHP combines the two functions into one.

Now I have sorted out the usage of the substr function and made a few examples to solve the confusion of newcomers. Experts please pass by.

The syntax of PHP substr function:

string substr(string string, int start, int [length])

The parameter string is the string to be operated on.

The parameter start is the starting position of the string you want to intercept. If start is a negative number, it means intercepting length characters starting from the penultimate start.

The optional parameter length is the length of the string you want to intercept. If not specified when using it, it will be taken to the end of the string by default. If length is a negative number, it means that it is intercepted from start to the right to the position of the length character from the end.

You may feel awkward when using this function at first, but if you understand the syntax of the PHP substr function, its functions are even better than left and right in asp, and it is very easy to use. . Let's take an example of its usage below.

1. Intercept from the 4th character to the end of the string, similar to left in asp:

<?php
 $str = "www.icoa.cn";
 echo substr($str,4); 
?>

Output:

icoa.cn

2. The PHP substr function intercepts 3 characters from the right, similar to right in asp:

<?php 
  $str = "www.icoa.cn";
  echo substr($str,-3);
?>

Output:

.cn

3. The PHP substr function intercepts 3 characters starting from the 4th character:

<?php
 $str = "www.icoa.cn";
 echo substr($str,4,3);
 ?>

Output:

ico

4. Sometimes we know the number of a string At the beginning and end, there are characters of variable length in the middle. At this time, in addition to using the regularity of the PHP substr function, we can also use substr to achieve it (of course there are N ways to get the characters in the middle. This is just an example of the application of substr):

This example removes the first 4 characters and the last 3 characters, and outputs the middle string:

<?php
 $str = "www.icoa.cn";
 echo substr($str,4,-3);
?>

Output:

icoa

———————— ————————

Copyright Statement: This article is an original article by CSDN blogger "Network Swordsman" and follows the CC 4.0 BY-SA copyright agreement. Please attach the original source link and this statement when reprinting.

Original link: https://blog.csdn.net/dongsg11200/article/details/9212777

Thank you for reading, I hope you will benefit a lot.

Recommended tutorial: "PHP Tutorial"

The above is the detailed content of The substr function intercepts part of the string in php (with detailed explanation). For more information, please follow other related articles on the PHP Chinese website!