The difference between php trim function ltrim function rtrim function

Everyone knows that PHP’s trim() function, ltrim() function, and rtrim() function can all remove spaces. So what are the differences in usage between the three? Now let me introduce them to you one by one.
1.php trim() function is to remove all spaces (in fact, to be precise, it is to remove all spaces in the string twice), for example:

$str=" love 59biye ";
echo ("---".trim($str)."---");//输出---love 59biye---

2.php ltrim() function is to remove the left side of the string Spaces, for example:

$str=" love 59biye ";
echo ("---".ltrim($str)."---");//输出---love 59biye ---

3.php The rtrim() function removes spaces on the right side of the string, for example:

$str=" love 59biye ";
echo ("---".ltrim($str)."---");//输出--- love 59biye---

Okay, everyone can see their specific differences.