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PHP method of accessing array elements
in_array() function
in_array() function Searches an array for a specific value and returns true if the value is found, false otherwise. 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:
$fruit = "apple"; $fruits = array("apple","banana","orange","pear"); if( in_array($fruit,$fruits) ) echo "$fruit 已经在数组中";
The third parameter is optional, it is mandatory in_array() considers types 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. If found, the color of the fruit will be output:
$fruit["apple"] = "red"; $fruit["banana"] = "yellow"; $fruit["pear"] = "green"; if(array_key_exists("apple", $fruit)){ printf("apple's color is %s",$fruit["apple"]); }
The result obtained by executing this code:
apple's color is red
array_search() function
array_search() function searches for a specified value in an array, if found, returns the corresponding key, otherwise 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 relevant information about the corresponding state:
$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])
Program The running results are as follows:
watermelon was founded on green.
array_keys() function
array_keys() function returns an array containing all keys found in the searched array. It has the following form:
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:
$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $keys = array_keys($fruits); print_r($keys);
The program running results are as follows:
Array ( [0] => apple [1] => banana [2] => watermelon )
array_values() function
The array_values() function returns all the values in an array and automatically provides a numerical index for the returned array. Its form is as follows:
array array_values(array array)
The following example will obtain the value of each element found in $fruits:
$fruits["apple"] = "red"; $fruits["banana"] = "yellow"; $fruits["watermelon"]="green"; $values = array_values($fruits); print_r($values);
The program running result is as follows:
Array ( [0] => red [1] => yellow [2] => green )
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