C++ Define at least 3 functions

Write a program that merges the numbers in two files and writes all the numbers into a third file. Your program takes input from two different files and writes its output to a third file. Each input file contains a list of numbers of type int in sorted order from the smallest to the largest. After the program is run, the output file will contain all the numbers in the two input files in one longer list in sorted order from smallest to largest You must provide the following user interface. The user input is depicted as Bold, but you do not need to display user input in bold. Please replace "YOUR NAME" with your name. Your program must first run a list of unit test cases and print unit testing results. Next, your program loads two input files and merges the numbers in the two files. ***Unit Test Cases Unit Test Case 1: Function Name show function name here. Case 1.1: explain test case 1.1 here (e.g-, input arguments) Case 1.1 passed. Case 1.2: explain test case 1.2 here (e.g., input arguments) Case 1.2 passed. Press any key to continue... Unit Test Case 2: Function Name show function name here. case 2.1: explain test case 2.1 here (e.g., input arguments) Case 2.1 passed. Case 2.2: explain test case 2.2 here (e.g., input arguments) Case 2.2 passed. Press any key to continue... Add more test cases below Press any key to continue