Place value of Integer digits

The process of program development starts with understanding the problem.
Problem: Find the highest place value exponent in a Base-10 integer.
Pre-requisite: i.e. 9,448,320,743 You may say, what does the 9 represent? (billion) what does the 4 next to the 9 represent? (hundred million) what number is in the hundred thousand's place?(3)
Base-10 123456 number is written as 1(100,000)+2(10000)+3(1000)+4(100)+5(10)+6(1) and that is 1(10^5)+2(10^4)+3(10^3)+4(10^2)+5(10^1)+6(10^0)
Analysis: In order to find the largest place value, we need to find the largest exponent of base 10.
We can find the highest exponent if we divide the integer by 10^exp where exp = {0,1,2,3,...}

i.e. 46578

num	exp	10exp	num/10exp
123456	0	1	123456
	1	10	12345
	2	100	1234
	3	1000	123
	4	10000	12
	5	100000	1
	6	1000000	0
	7	10000000	0

As you can see, we can find the highest exponent as soon as the result of the division is between 1 and 9.  So, we could solve this problem by iterating in a loop with an increment exp until the division result is between 1 and 9.

Design: Design involves creating a pseudo code or flow chart in order to develop the algorithm.

 start
   output "Welcome"
   output "Enter a number"
   input as num
   if input not a number then
       output  "Error: Better luck next time."
       return 1
   endif
   call findExp use num
   output "The exponent in: "
   output "Thanks for using my program."
stop

start findExp reference myNum
   call abs using myNum as myNum
   declare exp = 0
   while myNum / 10^exp > 10 then
      exp=exp+1
   endhile
   myNum = exp
return

Code: Now, that we have the basic idea, you can pick the language and code the problem.

#include<iostream>
#include<cmath>

using namespace std;
void findExp(int& num);

int main(){
    int num,exp;
    cout << "Welcome" << endl;
    cout << "Enter a number: ";
    cin >> num;
    if (!cin){              //validating user input
        cout << "Error: Better luck next time." << endl;
        return 1;
    }

    findExp(num);          //function call
    cout << "The exponent in: " << num << endl;
    cout << "Thanks for using my program." << endl;

    return 0;
}
void findExp(int& myNum){
    myNum = abs(myNum);
    int exp = 0;

    while (myNum / pow(10, exp) > 10){
        exp++;
    }
    myNum= exp;      //setting the new value to the referenced value
}