Commonly used functions of php to process strings

 1. Output string length*******

echo strlen("hello"); 

2. Compare two strings

 echo strcmp("ab","abc"); 

If two strings are the same, output 0, and if two strings are different, output -1. Note: case sensitive.

3. Compare two strings. Not case sensitive

 echo strcasecmp("AB","ab"); 

If two strings are the same, output 0, and if two strings are different, output -1.

4. Convert the string to lowercase

echo strtolower("ABCD"); 

5. Convert the string to uppercase

echo strtoupper("abvcd"); 

6. Split string ******

$arr = explode("|","a|vdf|dfs|sdf");
var_dump($arr); 

7. Splicing strings*******

$arr = explode("|","a|vdf|dfs|sdf");
echo implode("*",$arr);

Output:

8. Replace string *****

echo substr_replace("hellommworld","**",5,2); 

Replace 2 characters starting from index 5 (replace the specified position)

9. Find and replace string ****

echo str_replace("l","*","hellommworld"); 

Find l, replace with *

10. Intercept string******

echo substr("hello",0,2);
echo substr("张三",0,3);

中文字符串，一个字符占三个索引

Output

11. Find the position where the string appears: 

strrpos()  -Find the position of the last occurrence of a string in another string (case sensitive)

strpos()  -Find the position of the first occurrence of a string in another string (case sensitive)

stripos()  -Find the first occurrence of a string in another string (not case sensitive)

strripos()  -Find the position of the last occurrence of a string in another string (not case sensitive)