Detailed description of the specific functions of the PHP function str_replace _ PHP Tutorial-php Tutorial

Detailed description of the str_replace function of PHP. During the actual period, we read the PHP function str_replace in the book PHP and MySQLWeb development. a small prompt says: we can use arrays for all three of str_replace.During this time, I read the book "PHP and MySQL Web development" and saw the PHP function str_replace explanation. I wrote a small note: Three of str_replace can be passed in using arrays, but the explanation is relatively simple, so I decided to test the execution result of the function when each parameter is passed into the array.

Function prototype: mixed str_replace (mixed needle, mixed new_needle, mixed haystack [, int & count]);
Needle: string to be replaced, new_needle: string to be replaced, haystack: Operation string, count: number of replacements (optional]

We focus on the execution method of the first three items using arrays:
When no array is used, the PHP function str_replace replaces all needle directly with new_needle and returns the replaced string. For example, str_replace ("m", "n", "my name is jim! ") Ny nane is jin!

1. use arrays only for needle.

Example: str_replace (array ('M', 'I'), 'n', "my name is jim! "); Return value: ny nane ns jnn!
It can be seen that each string in the array is replaced by the function sequence, and the replaced string is returned.

2. use arrays only for new_needle.

Example of the str_replace function in PHP: str_replace ('M', array ('N', 'z'), "my name is jim! N ") return: Arrayy naArraye is jiArray!
This replacement is interesting. if you only use an Array for the second parameter, the function uses it as a string Array and replaces all needle with an Array.

3. use arrays only for haystack.

Example: str_replace ("m", "n", array ("my name is jim! "," The game is over! ") The execution result of this statement returns an array, that is, the result after the input two strings are replaced.
If the output array content is: ny nane is jin! The gane is over!

4. use arrays for both needle and new_needle.

Example: str_replace (array ("m", "I"), array ("n", "z"), "my name is jim! ") Return value: ny nane zs jzn!
View the execution result. if the first two parameters use an array, the function replaces each object string in the array and the first item in needle with the first item in new_needle. And so on.
If the needle array is longer than new_deedle, for example, str_replace (array ("m", "I", "s"), array ("n", "z "), "my name is jim! "); Return: ny nane z jzn! It can be seen that the strings that come out of the needle array are replaced with empty strings.
If the new_needle array is longer than the needle, for example, str_replace (array ("m", "I"), array ("n", "z", "x "), "my name is jim! ") Returns ny nane zs jzn! The excess new_needle items are ignored.

5. All three parameters use arrays.

Example of the str_replace function in PHP: str_replace (array ("m", "I"), array ("n", "z"), array ("my name is jim! "," The game is over ") returned array content: ny nane zs jzn! The gane zs over
This is easy to understand. replace the two strings.

During this time, I saw the PHP function str_replace in the book PHP and MySQL Web development. I wrote a small note: Three of str_replace can be passed in using arrays ,...