How to determine whether certain values ​​exist in an array in php

In PHP, when we need to determine whether an array contains certain values, we can use the in_array() function, which is used to find the specified value in the array and return a Boolean value (true or false). The following is the syntax of the function:

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

Among them, the first parameter needle represents the value to be found, the second parameter haystack represents the array to be searched in, and the optional third parameter strict specifies whether Perform strict data type comparison, default is false.

The following are some examples showing how to use the in_array() function to determine whether certain values ​​exist in the array:

1. Determine whether the array contains an integer:

$nums = array(1, 3, 5, 7, 9);
if (in_array(3, $nums)) {
    echo "数组中包含数字 3。";
} else {
    echo "数组中不包含数字 3。";
}

This code will output: "The array contains the number 3." because the array $nums contains the number 3.

2. Determine whether the array contains a certain string:

$fruits = array("苹果", "香蕉", "橙子", "葡萄");
if (in_array("橙子", $fruits)) {
    echo "数组中包含橙子。";
} else {
    echo "数组中不包含橙子。";
}

This code will output: "The array contains oranges.", because the array $fruits contains a string "orange".

3. Use the in_array() function for strict data type comparison:

$nums = array(1, 3, 5, 7, 9);
if (in_array("1", $nums, true)) {
    echo "数组中包含字符串 '1'。";
} else {
    echo "数组中不包含字符串 '1'。";
}

This code will output: "The array does not contain the string '1'.", because Strings and integers are not equal when doing strict data type comparisons.

In short, the in_array() function is a very practical array function in PHP. It can quickly determine whether an array contains certain values. It is one of the functions we often use in actual development.

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