array combine and array merge difference

 array_combine and array_merge are both PHP functions used for working with arrays, but they serve different purposes and have distinct behaviors:

1. array_combine:

   • Syntax: array_combine(array $keys, array $values): array|false

   • Purpose: Combines two arrays into a single associative array, using one array for keys and another for values.

   • Example:

     php
     $keys = ['name', 'age', 'country'];
     $values = ['John', 30, 'USA'];
     
     $combinedArray = array_combine($keys, $values);
     // Result: ['name' => 'John', 'age' => 30, 'country' => 'USA']
     

   • Notes:

     • The number of elements in both arrays should be equal.
     • If the arrays have different lengths, array_combine returns false.

2. array_merge:

   • Syntax: array_merge(array ...$arrays): array

   • Purpose: Merges multiple arrays into a single array, preserving numeric keys and overwriting values with the same key from later arrays.

   • Example:

     php
     $array1 = ['a' => 'apple', 'b' => 'banana'];
     $array2 = ['b' => 'blueberry', 'c' => 'cherry'];
     
     $mergedArray = array_merge($array1, $array2);
     // Result: ['a' => 'apple', 'b' => 'blueberry', 'c' => 'cherry']
     

   • Notes:

     • Keys are preserved unless they are numeric and consecutive, in which case they are reindexed starting from zero.
     • Values with the same key in later arrays overwrite earlier ones.

In summary:

• array_combine is used to create an associative array from two arrays, using one array for keys and another for values.
• array_merge is used to merge multiple arrays into a single array, combining their elements while preserving or reindexing keys as necessary.