How to add characters to the beginning of a string in php

Two implementation methods: 1. Use the string connector "." to splice the specified character at the beginning of the string, and the syntax is "specified character. string"; 2. Use the substr_replace() function to add the specified character to the beginning of the string. To insert the specified character at the beginning of the string, you only need to set the second parameter of the function to the specified character, and set the third and fourth parameters to 0. The syntax is "substr_replace(string, specified character, 0, 0)" .

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

In PHP, you can use string concatenation or substr_replace() inserts to add characters to the beginning of the string.

Method 1: Use the string connector "." to splice

String connector . can combine two or more strings are concatenated into a new string.

You only need to use the string connector "." to splice the specified characters at the beginning of the original string

<?php
header("Content-type:text/html;charset=utf-8");
$str1="hello";
echo "原字符串：".$str1."<br>";
$ch="A";
echo "指定字符：".$ch."<br>";
$str=$ch.$str1;
echo "在字符串首部增加指定字符后：".$str;
?>

Method 2: Use The substr_replace() function performs insertion

The substr_replace() function replaces part of a string with another string.

substr_replace(string,replacement,start,length)

Parameters	Description
string	Required . Specifies the string to check.
replacement	Required. Specifies the string to be inserted.
start	Required. Specifies where in the string to begin replacement. Positive number - starts at the specified position in the string Negative number - starts at the specified position from the end of the string 0 - at the first character in the string Start at
length	Optional. Specifies how many characters to replace. The default is the same as the string length. Positive number - the length of the string to be replaced Negative number - the number of characters to be replaced from the end of the string 0 - insert instead of replace

• Return value: Returns the replaced string.
  

#You only need to set the second parameter of the function to the specified character, the third parameter to 0, and the fourth parameter to 0.

<?php
header("Content-type:text/html;charset=utf-8");
$str1="hello";
echo "原字符串：".$str1."<br>";
$ch="W";
echo "指定字符：".$ch."<br>";
$str=substr_replace($str1,$ch,0,0);
echo "在字符串首部增加指定字符后：".$str;
?>

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