Summary of methods of finding and searching array elements in PHP_PHP Tutorial

Summary of PHP methods of finding and searching array elements

Finding, filtering and searching array elements are some common functions of array operations. Here are some related functions.

in_array() function

The in_array() function searches for a specific value in an array and returns true if the value is found, otherwise it returns false. Its form is as follows:

boolean in_array(mixed needle,array haystack[,boolean strict]);

Look at the following example to find whether the variable apple is already in the array. If it is, output a piece of information:

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$fruit = "apple"; $fruits = array("apple","banana","orange","pear"); if( in_array($fruit,$fruits) ) echo "$fruit 已经在数组中";

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$fruit = "apple";

$fruits = array("apple","banana","orange","pear");

if( in_array($fruit,$fruits) )

echo "$fruit is already in the array";

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$fruit["apple"] = "red"; $fruit["banana"] = "yellow"; $fruit["pear"] = "green"; if(array_key_exists("apple", $fruit)){ printf("apple's color is %s",$fruit["apple"]); }

The third parameter is optional and forces in_array() to consider the type when searching.

array_key_exists() function

If a specified key is found in an array, the function array_key_exists() returns true, otherwise it returns false. Its form is as follows:

boolean array_key_exists(mixed key,array array);

The following example will search for apple in the array key, and if found, will output the color of the fruit:

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$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $founded = array_search("green", $fruits); if($founded) printf("%s was founded on %s.",$founded, $fruits[$founded])

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$fruit["apple"] = "red";

$fruit["banana"] = "yellow";

$fruit["pear"] = "green";

if(array_key_exists("apple", $fruit)){

printf("apple's color is %s",$fruit["apple"]);

}

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$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $keys = array_keys($fruits); print_r($keys);

The result of executing this code: The code is as follows: apple's color is red array_search() function The array_search() function searches for a specified value in an array and returns the corresponding key if found, otherwise it returns false. Its form is as follows: mixed array_search(mixed needle,array haystack[,boolean strict]) The following example searches $fruits for a specific date (December 7), and if found, returns information about the corresponding state:

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$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $founded = array_search("green", $fruits); if($founded) printf("%s was founded on %s.",$founded, $fruits[$founded])

The results of running the program are as follows: The code is as follows: watermelon was founded on green. array_keys() function The array_keys() function returns an array containing all keys found in the searched array. Its form is as follows: array array_keys(array array[,mixed search_value]) If the optional parameter search_value is included, only keys matching that value will be returned. The following example will output all arrays found in the $fruit array:

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$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $keys = array_keys($fruits); print_r($keys);

The results of running the program are as follows:

The code is as follows:

Array ( [0] => apple [1] => banana [2] => watermelon )

array_values() function

The

array_values() function returns all values ​​in an array and automatically provides numerical indexes for the returned array. Its form is as follows:

array array_values(array array)

The following example will get the value of each element found in $fruits:

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$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $values = array_values($fruits); print_r($values);

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$fruits["apple"] = "red";

$fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $values ​​= array_values($fruits); print_r($values);

The results of running the program are as follows:

The code is as follows:

Array ( [0] => red [1] => yellow [2] => green )

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