Introduction to the use of in_array() function in PHP function library

In PHP development, arrays often need to be processed and modified, and the in_array() function is one of the most commonly used functions when processing arrays. This article will introduce how to use this function.

The in_array() function is to search for the specified value in the array and return true if found, otherwise false. The syntax of this function is as follows:

in_array($value, $array, $strict)

where $value is the value to be found, $array is the array to be found, and $strict is an optional parameter used to specify whether to force check the variable type. By default, the value of $strict is false, which means that only the values ​​of the variables are checked for equality, and the variable types are not checked.

The following are some usage examples of in_array():

1. Check whether a value exists in the array

$numbers = array(1, 2, 3, 4, 5);
if (in_array(3, $numbers)) {
    echo "3 存在于数组中";
} else {
    echo "3 不存在于数组中";
}

The above code will output "3 exists in the array".

2. Checks whether a value exists in the array and forces type checking when comparing

$numbers = array(1, 2, 3, 4, 5);
if (in_array("3", $numbers, true)) {
    echo "3 存在于数组中";
} else {
    echo "3 不存在于数组中";
}

The above code will output "3 does not exist in the array" because in The comparison forces type checking, so the string "3" is not equal to the integer 3.

3. Find whether the key name in the array has the specified value

$ages = array("Peter" => 35, "Ben" => 28, "Joe" => 40);
if (in_array(35, $ages)) {
    echo "35 的键名是：" . array_search(35, $ages);
} else {
    echo "35 不存在于数组中";
}

The above code will output "The key name of 35 is: Peter" because "Peter" in the array "The value corresponding to the key name is 35.

Summary:

The above is the introduction and examples of the use of in_array() function. I hope it will be helpful to you in using this function in PHP development. This function is used frequently in actual development and can effectively improve the efficiency and readability of the code.

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