PHP removes the last character of the string substr () usage

Used today in the project to remove the last character in the string
The original string 1,2,3,4,5,6,
Remove the last character "," and the end result is 1,2,3,4,5,6
The code is as follows:
Copy CodeThe code is as follows:
$str = "1,2,3,4,5,6,";
$newstr = substr ($str, 0,strlen ($STR)-1);
Echo $newstr;

The system's own functions can also achieve this effect, two ways:
1) substr ($str, 0,-1)
2) RTrim ($str, ",")

substr
Takes a partial string.
Syntax: String substr (string string, int start, int [length]);
return value: String
Function type: Data processing
Content Description
This function extracts the length character of the string from the start of string strings. If start is a negative number, it is counted from the end of the string. If the parameter length that can be omitted exists but is negative, it is taken to the penultimate length character.
Usage examples
Copy CodeThe code is as follows:
?
echo substr ("abcdef", 1, 3); Return "BCD"
echo substr ("ABCdef",-2); Return to "EF"
echo substr ("ABCdef",-3, 1); Return "D"
echo substr ("abcdef", 1,-1); Return to "BCDE"
?>

PHP RTrim () function
Definitions and usage
The RTrim () function deletes white space characters or other predefined characters from the end of the string. Same chop () function.
Grammar
RTrim (string,charlist) parameter description
String required. Specify the string to convert.
Charlist Optional. Specify which characters to remove from the string.
If this argument is not set, all the following characters are deleted:
"I"-ASCII 0, NULL
"\ T"-ASCII 9, tab
"\ n"-ASCII 10, New line
"\X0B"-ASCII 11, Vertical tab
"\ r"-ASCII 13, carriage return
""-ASCII 32, space
Usage examples