How to concatenate two integer arrays without using loop in C ?

Given two arrays such that first array has enough extra space to accommodate elements of second array. How to concatenate second array to first in C without using any loop in program?

Example:

Input: arr1[5] = {1, 2, 3}
       arr2[]  = {4, 5}
Output: arr1[] = {1, 2, 3, 4, 5}

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Hint: We may use library functions in C.

The idea is to use memcpy() or memmove() in C.

// arr1[] is of size m+n and arr2[] is of size n. This function
// appends contents of arr2[] at the end of arr1[]
void concatenate(int arr1[], int arr2[], int m, int n)
{
   memcpy(arr1 + m, arr2, sizeof(arr2));
}

See this for complete running code.

Thanks to Utkarsh Trivedi for suggesting above solution.