How to replace strings in php ignoring case

Method to ignore case replacement: 1. Use str_ireplace() function, syntax "str_ireplace(search value, replacement value, string)"; 2. Use substr_replace() function, syntax "substr_replace(string) ,replacement value,start replacement position)".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Method 1: Use The str_ireplace() function

replaces the character "WORLD" (case-insensitive) in the string "Hello world!" with "Shanghai":

<?php
echo str_ireplace("WORLD","Shanghai","Hello world!");
?>

Output :

Hello Shanghai!

Description:

str_ireplace() function replaces some characters in a string (not case-sensitive).

This function must follow the following rules:

• If the searched string is an array, then it will return an array.

• If the searched string is an array, then it will find and replace each element in the array.

• If you need to search and replace the array at the same time, and the elements that need to be replaced are less than the number of found elements, the excess elements will be replaced with empty strings

• If you search an array and replace only one string, the replacement string will work for all found values.

Syntax

str_ireplace(find,replace,string,count)

Parameters	Description
find	Required. Specifies the value to look for.
replace	Required. Specifies a value that replaces the value in find.
string	Required. Specifies the string to be searched for.
count	Optional. A variable counting the number of substitutions.

Method 2: Use the substr_replace() function

Replace "Hello" with "world":

<?php
echo substr_replace("Hello","world",0);
?>

Output:

world

Description:

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 numbers - Replace starting at the specified position in the string Negative numbers - Replace starting at the specified position from the end of the string 0 - Replace at the specified position in the string Start replacing the first character in
length	is optional. Specifies how many characters to replace. The default is the same as the string length. Positive number - the length of the string being replaced Negative number - indicates the number of characters from the end of the substring to be replaced string. 0 - Insert instead of replace

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