Usage and precautions of php array function in_array

This article introduces usage examples of the PHP array function in_array and some issues that should be paid attention to during use. Friends in need can refer to it.

There are many functions for operating arrays in PHP, and in_array is one of them.

in_array function An array used to check whether a value exists, that is, it can determine whether a specified value exists in the current array.

in_array (PHP 4, PHP 5)

in_array — Check if a value exists in an array

Instructions bool in_array ( mixed $needle , array $haystack [, bool $strict ] )

Search for needle in haystack and return TRUE if found, otherwise return FALSE.

If the value of the third parameter strict is TRUE, the in_array() function will also check whether the type of needle is the same as that in haystack. Tip 1: If needle is a string, the comparison is case-sensitive. Tip 2: Before PHP version 4.2.0, needle was not allowed to be an array.

Example 1, in_array() example

<?php
$os = array("Mac", "NT", "Irix", "Linux");
if (in_array("Irix", $os)) {
echo "Got Irix";
}
if (in_array("mac", $os)) {
echo "Got mac";
}
?>

The second condition fails because in_array() is case sensitive, so the above program reads: Got Irix

Example 2, in_array() strict type checking example

<?php
$a = array('1.10', 12.4, 1.13);

if (in_array('12.4', $a, true)) {
echo "'12.4' found with strict check\n";
}
if (in_array(1.13, $a, true)) {
echo "1.13 found with strict check\n";
}
?>

Output: 1.13 found with strict check

Example 3, using array as needle in_array()

<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');

if (in_array(array('p', 'h'), $a)) {
echo "'ph' was found\n";
}
if (in_array(array('f', 'i'), $a)) {
echo "'fi' was found\n";
}
if (in_array('o', $a)) {
echo "'o' was found\n";
}
?>

Output: 'ph' was found 'o' was found

Things to note when using the php array function in_array:

If: First declare an array as: $arr = array(*);

Then there are: in_array(0, $arr) == true This is inconsistent with reality. Smart one, do you understand?

Solution: in_array(strval(0), $arr, true)) Only by judging in this way can you get the correct result.

This article uses a few small examples to help you learn and understand the usage of the PHP array function in_array, and explains a detail that needs to be paid attention to.

Programmer’s Home, I wish you all the best in your studies and progress.