PHP Learning Notes-arrays (4)

Array_key_exists (Key,array);

Role:

Whether there is a key in array arrays

Return:

BOOL exists return True, there is no return false

Example: whether the name exists in the array

$arr = Array (' name ' = = ' char ', ' age ' = +, ' sex ' = ' f '); if (array_key_exists (' name ', $arr)) {echo ' name exists ';} else {echo ' name does not exist ';} Output: Name exists

Array_keys (array, value, BOOL);

Role:

Gets the key value in the array

Parameters:

Array: Arrays

Value: Optional, specifying the value in the array

BOOL: Optional default not false, used with value values, default does not need to match the type of value, true matches the type.

return value:

Returns an array containing the key

Example:

$arr = Array (' name ' = = ' char ', ' age ' = +, ' sex ' = ' f ');       $keys = Array_keys ($arr); Gets the key value of the array $key 1 = Array_keys ($arr, ' 21 '); Gets the value 21 for the key $key 2 = Array_keys ($arr, ' + ', true); Gets the key value of value 21, and value is the string Print_r ($keys); Print_r ($key 1); Print_r ($key 2); Output: Array ([0] + = name [1] = age [2] = = Sex) array ([0] = age) Array ()

Array_map (string, array);

Role:

With a custom function, each parameter in the array is processed and returned

Parameters:

String: Name of function

Array: Arrays

return value:

Returns the new array

Example: Multiply each parameter of an array by 2

function MyFunction ($v) {return $v *;} $arrOne = Array (' A ' =>1, ' b ' = = 2, 3, 4, 5); $res = Array_map (' myFunction ', $arrOne); Print_r ($res); Output: Array ([A] = 2 [b] = 4 [0] = 6 [1] = 8 [2] = 10)

Array_merge (Array1, array2);

Role:

Merging one or more arrays

Parameters:

Array1: Merged array 1

Array2: merged array 2

return value:

The merged array

Example:

$arrOne = Array (' a ' = = ' Blue ', ' b ' = ' yellow '); $arrTwo = Array (' a ' = = ' red ', ' d ' = ' purple '); $res = Array_merge ($arrOne, $ARRTWO); Print_r ($res); Output: Array ([a] = red [b] = yellow [d] = purple)

Array_merge_recursive (Array1, arrray2);

Role:

Recursive merging of multiple arrays, unlike Array_merge (), which does not overwrite when processing the value of the same key name

Parameters:

Array1: Merged array 1

Aray2: merged array 2

return value:

The merged array

Example:

$arrOne = Array (' a ' = = ' Blue ', ' b ' = ' yellow '); $arrTwo = Array (' a ' = = ' red ', ' d ' = ' purple '); $resRe = Array_merge_recursive ($arrOne, $ARRTWO); Print_r ($resRe);    Output: Array ([a] = = Array ([0] = blue [1] = red) [b] = Yellow [d] = purple)

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PHP Learning Notes-arrays (4)