How to determine whether a character is in an array in php

In PHP programming, we often encounter situations where we need to determine whether a character is in an array. At this time, we can use PHP's in_array function to quickly determine whether the character is in the array. The following article will introduce in detail how to use the in_array function to determine whether a character is in an array.

1. Introduction to the usage of in_array function

The function of in_array function is to determine whether a value exists in the array. It accepts two parameters. The first parameter is the string to be found. The second parameter is the array to be searched. The specific form of the function is:

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

Among them, needle is the value to be searched, haystack is the array to be searched, and strict is boolean (optional). If TRUE is passed, the function will also check the type of needle and Whether the values ​​in haystack are of the same type.

If the needle value to be found appears in the haystack array, return TRUE, otherwise return FALSE.

2. Use the in_array function to determine whether the character is in the array

Below we will demonstrate a specific example of how to use the in_array function to determine whether the character is in the array.

Example 1: Determine whether the character is in the index array

$arr = array('a','b','c','d','e');
if (in_array('c',$arr))
{
    echo "c 存在于arr";
}
else
{
    echo "c 不存在于arr";
}

In the above code, we define an index array $arr, and then use the in_array function to determine whether the character 'c' is in the array. Because 'c' exists in the array, "c exists in arr" is printed.

Example 2: Determine whether a character is in an associative array

In an associative array, you can also use the in_array function to check whether a character exists in the array. In fact, inside the function, PHP will first compare the character to be found with all the values ​​in the array. If it is an associative array, it will only compare whether the value in the array is equal to the value to be found.

$arr = array('a'=>1, 'b'=>2, 'c'=>3, 'd'=>4, 'e'=>5);
if (in_array(3, $arr))
{
    echo "3 存在于arr";
}
else
{
    echo "3 不存在于arr";
}

In the above code, we define an associative array $arr, and then use the in_array function to determine whether the number 3 is in the array. Because the number 3 exists in the array, "3 exists in arr" is printed.

3. Summary

This article mainly introduces how to use the in_array function to determine whether a character or number is in an array, including the main function, syntax and usage of its function.

In PHP programming, the in_array function is a very commonly used function, especially when values ​​need to be checked. I hope that the introduction of this article can help readers better understand and apply the in_array function.

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