Summary of PHP array and string conversion functions_PHP tutorial

1. Convert a string into an array
str_split() is used to convert a string into an array
Syntax:

Copy code The code is as follows:

str_split(string,length)
//string is required , is the string to be split;
//length is optional, specifying the length of each array element

tips:
If length is less than 1, the str_split() function will return false.
If length is greater than the length of the string, the entire string will be returned as the only element of the array.
Example:

Copy code The code is as follows:

$str="www.baidu.com";
print_r(str_split($str));
?>

2. String splitting function
explode() function splits a string into an array.
Syntax:
explode(separator,string,limit)
//separator is required and specifies the basis for splitting the string, for example: " "(space) "| " "," etc.
//string is required and is the string to be operated on
//limit is optional and specifies the maximum number of array elements returned.
Example:

Copy code The code is as follows:

$types="doc|docx|ppt|pptx|xls|xlsx|zip|rar";
print_r(explode("|",$types));
?>

3. Convert an array into a string
Use the implode() function to combine the array elements into a string
Syntax:

Copy code The code is as follows:

implode(separator,array)

//seperator It is optional and specifies the content placed between array elements. The default is "" (empty string)

//array is required and is an array to be combined into a string

tips: Although the separator parameter is optional. However, for backward compatibility, it is recommended that you use two parameters. implode() can accept two parameter orders. However, due to historical reasons, explode() does not work. You must ensure that the
separator parameter comes before the string parameter. Example:

<?php<BR>$arr = array('Hello','World!','Beautiful','Day!');<BR>echo implode(" ",$arr);<BR>?>

4. Find another character in the string
Use strpos() or strstr() function
strpos() function returns the first occurrence of the string in another string location.
If the string is not found, return false.
Syntax:

Copy code The code is as follows:

strpos(string,find,start )
//string is required, indicating the searched string
//find is required, indicating the searched string
//start is optional. Specifies the location from which to start the search.

tip:
This function is case sensitive
Example:

Copy code The code is as follows:

$str="HellO neo";
$find1="O";
$find2="o";
echo strpos($str,$find1);
echo "
";
echo strpos($str,$find2);
?>

Output result:

Copy code The code is as follows:

4
8

5. Intercept part of the characters in the string
substr() function returns a part of the string
Syntax:

Copy code The code is as follows:

substr(string,start,length)
//string is required and is required to be returned. part of a string.
/*Required. Specifies where in the string to begin.
Positive number - Starts at the specified position in the string
Negative number - Starts at the specified position from the end of the string
0 - Starts at the first character in the string
*/
/*Optional. Specifies the length of the string to be returned. The default is until the end of the string.
Positive number - Returns
from the position of the start parameter Negative number - Returns
*/

tips:
If start is a negative number and length is less than or equal to start, then length is 0.
Example;

Copy code The code is as follows:

$str="Hello world!";
echo substr($str,0);
echo "
";
echo substr($str,6,5);
?>

6. Get the string length
strlen() function is used to calculate the length of the string.
Example:

Copy code The code is as follows:

$str="Hello world!";
echo strlen($str);
?>
//The output result is 12

7 .Convert string to uppercase
strtoupper() function converts string to uppercase.
Example:

Copy code The code is as follows:

$str="Hello world!";
echo strtoupper($str);
?>
//The output result is: HELLO WORLD!

8. Convert the string to lowercase
The strtolower() function converts the string to lowercase.
Example:

Copy code The code is as follows:

$str="Hello World!";
echo strtolower($str);
?>

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