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PHP substr: Main Tips
- PHP
substris one of the most common PHP string functions. It returns a part of a string. - The first argument specifies a string which will be trimmed.
- The second argument specifies the position of the trim start. The third argument specifies the length of the string to be returned.
- The start and length arguments can also be negative numbers.
Function Explained
PHP substr function returns the trimmed string. In other words, the method extracts a part of a string. In case of failure or an empty string, False is returned.
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Syntax: Scheme and Parameters
As with all PHP string functions, using correct syntax is crucial here. Let's look at how the correct syntax for PHP substr function should look like:
substr(string, start, length)
Now, let's go through every element step by step to get a better understanding of what each parameter of the substr PHP function represents:
| Parameter | Description |
|---|---|
| string | Necessary. Specifies the exact string to trim. |
| start | Necessary. Sets a position for the start of trimming (counting from the start of the string if the number is positive, from the end - if it's negative). 0 sets start at the first character. |
| length | Optional. Sets the length of the returned string (measured from the start parameter is a the number is positive, from the end - if it's negative). The default value is 0. |
Note: If the second argument has a negative value and the third argument is less than or equal to the second argument, the third argument (length) is automatically set to 0.
More Code Examples
The example below displays a few cases of using the start argument alone in the substr PHP function. The comments next to every case explain what will be returned:
<?php
echo substr("Lama is the best pet", 8);
echo substr("Lama is the best pet", 1);
echo substr("Lama is the best pet", 5);
echo substr("Lama is the best pet", -3);
echo substr("Lama is the best pet", -8);
?>Now, the example below displays cases when start and length arguments are used together. Again, the comments next to every case display what will be returned:
<?php
echo substr("Lama is the best pet", 0, 16);
echo substr("Lama is the best pet", 2, 9);
echo substr("Lama is the best pet", 0, 4);
echo substr("Lama is the best pet", 0, -4);
echo substr("Lama is the best pet", -9, -4);
?>
