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In PHP programming, string operations are very common. Sometimes we need to count the number of occurrences of each character in a string. In this case, we can use PHP's count_chars() function. This article will introduce in detail how to use PHP's count_chars() function.
1. Overview of count_chars() function
The count_chars() function is a built-in function in PHP, used to count the number of occurrences of each character in a string.
bool count_chars ( string $string [, int $mode = 0 ] )
Parameter description:
$string: A string in which the number of occurrences of characters needs to be counted.
$mode: Optional parameter, specify the return form:
2. Use the count_chars() function to count the number of times a character appears
The following is a simple example of.
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The output result is as follows:
Array
(
[32] => 1 [33] => 1 [72] => 1 [101] => 1 [108] => 3 [111] => 2 [114] => 1 [119] => 1 [100] => 1
)
As you can see from the result, the count_chars() function returns An array is created, the keys of the array are ASCII code values, and the values are the number of times a character appears. For example, the ASCII code value of the character "H" is 72, and it appears once in the string.
The following example demonstrates how to return a list of all non-repeating characters in a string.
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The output result is as follows:
H
e
l
o
W
r
d
!
As you can see from the results, the count_chars() function returns a string containing all non-repeating characters in the string. Moreover, we used the str_split() function to convert the string into a character array and output it one by one in the foreach loop.
3. Summary
This article introduces in detail the usage of the count_chars() function in PHP, including counting the number of occurrences of each character and returning a list of non-repeating characters. We can use this function to quickly count the characters in the string, which brings great convenience to our programming.
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