How to write a C++ program.

Additive persistence is a property of the sum of the digits of an integer. The sum of the digits is found, and then the summation of digits is performed creating a new sum. This process repeats until a single integer digit is reached. Consider the following example:

1. The beginning integer is 1234

2. Sum its digits is 1+2+3+4 = 10

3. The integer is now 10

4. The sum of its digits is 1 + 0 = 1

5. The integer is 1. When the value reaches a single digit, we are finished. This final integer is the additive root

Program Specifications

The program should run as follows.

1) Gather input as a redirection from a file input.txt. The program ends under one of the following circumstances a. the next gathered integer is a negative number. b. if all the integers from the file have been processed.

2) If the given integer is a single digit, report its additive persistence as 0 and its additive root as itself on a single line as two space separated numbers

3) For each multidigit, non-negative, integer output on a single line the two space separated numbers: a. the integer's additive persistence b. the integer's additive root

How to write a C++ program.