array_merge() merges the elements of one or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array.
If the input arrays have the same string keys, then the later value for that key will overwrite the previous one. If, however, the arrays contain numeric keys, the later value will not overwrite the original value, but will be appended.
If only one array is given and the array is numerically indexed, the keys get reindexed in a continuous way.
Example 1. array_merge() example
The above example will output:
Example 2. Simple array_merge() example
Don't forget that numeric keys will be renumbered!
If you want to completely preserve the arrays and just want to append them to each other, use the + operator:
The numeric key will be preserved and thus the association remains.
The behavior of array_merge() was modified in PHP 5. Unlike PHP 4, array_merge() now only accepts parameters of type array. However, you can use typecasting to merge other types. See the example below for details.