How to determine if a number is in an array in php

Method: 1. Use "in_array(value, array)", if TRUE is returned, it exists, otherwise it does not exist; 2. Use "array_search(value, array)", if the key name is returned, then it exists, return If FALSE, it does not exist; 3. Use "array_keys (array, value)". If the returned array is empty, it does not exist.

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

php determines a number Method of whether it is in an array

1. Use in_array()

in_array() function to find whether the array contains a certain value , returns TRUE if it exists, and returns FALSE if it does not exist. The syntax format is as follows:

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

The parameter description is as follows:

• $needle: is the value to be searched. If $needle is a string, the comparison is case-sensitive;
• $array: is the array to be searched;
• $strict: is an optional parameter, the default is FALSE.
  •             If $strict is empty or FALSE, the in_array() function will only check whether the value of $needle is equal to the value in $array;
  •             If $strict is TRUE, the in_array() function, in addition to checking the values ​​in $needle and $array, also compares their types for equality.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$array = [3,"hello",2,"2","1",4,6];
if(in_array(1, $array, true)){
    echo &#39;数组中包含1<br>&#39;;
}else{
    echo &#39;数组中不包含1<br>&#39;;
}
if(in_array(1, $array)){
    echo &#39;数组中包含1<br>&#39;;
}else{
    echo &#39;数组中不包含1<br>&#39;;
}
?>

2. Use array_search()

array_search(value, array,strict) The function searches for a key value in the array; if the specified key value is found in the array, the corresponding key name is returned, otherwise FALSE is returned.

Parameter strict is optional. If this parameter is set to TRUE, the function searches the array for elements of the same data type and value. Possible values:

• true

• #false - Default

  If set to true, checks the given in the array The value types, number 5 and string 5 are different (see Example 2).

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$array = [3,"hello",2,"5","1",4,6];
if(array_search(5, $array, true)){
    echo &#39;数组中包含5<br>&#39;;
}else{
    echo &#39;数组中不包含5<br>&#39;;
}
if(in_array(5, $array)){
    echo &#39;数组中包含5<br>&#39;;
}else{
    echo &#39;数组中不包含5<br>&#39;;
}
?>

3. Use array_keys()

rray_key() function to get parts of the array Or all key names, the syntax format of this function is as follows:

array_keys($array [, $search_value = null [, $strict = false]])

The parameter description is as follows:

• $array: required parameter, which is the array to be operated;
• $search_value: Optional parameter. If the parameter is empty, the function will return all the key names in the array. If this parameter is specified, the function will only return the key name with the value $search_value;
• $strict: Optional parameter to determine whether to use strict mode when searching. $strict defaults to false, which is non-strict mode. Only types are compared during search, not types. If $strict is set to true, that is Strict mode, compares both value and type when searching, equivalent to ===.

array_key() function will return the obtained array key name in the form of an array.

Find the key name of the specified key value. If the returned array is an empty array, it is not in the array.

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$array = [3,"hello",2,"5","1",4,6];
if(array_keys($array,5, true)==[]){
    echo &#39;数组中不包含5<br>&#39;;
}else{
    echo &#39;数组中包含5<br>&#39;;
}
if(array_keys($array,5)==[]){
    echo &#39;数组中不包含5<br>&#39;;
}else{
    echo &#39;数组中包含5<br>&#39;;
}
?>

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