Making a simple addition calculator with a char array--how do I make the leading '0's blank?

[Tatortotts]

Hi everyone, I'm in an introductory C++ course and we're learning how to add arrays together. For homework, I had to create a program that would take an input number with between 0-20 and store it in a size-20 char array. This was done two times.

I then had to take those two char arrays, convert each digit in the same slot to integers, add them together, and store the remaining int as a char in a third array (accounting for numbers that went over 10, as well).

Luckily I've already done all of that, but now I'm having a problem with the output (performed in the OutputNumber function). When storing the values in the arrays, we were told to fill all other empty array spots with char 0 values. When outputting, though, the number should not have any leading zeroes visible.

Here's an example of what an interaction with my current program would look like:

Please enter your first number
How many digits are in your number? 6
Please enter your number starting with the LEAST significant digit: 123456
Please enter your second number
How many digits are in your number? 7
Please enter your number starting with the LEAST significant digit: 1234567

00000000000000654321 + 00000000000007654321 = 00000000000008308642

The last line should just show "654321 + 7654321 = 8308642".
I've tried setting up a simple if statement to exclude zeroes, but obviously that excludes any zeroes that are actually contained in the number as well, which is a no no.

Any help will be greatly appreciated. Here's my code:

#include <iostream>
using namespace std;

const int SIZE=20;
char overflow;
void InitNumber(char[], char[], int, int);
void AddArrays(char[], char[], char[], char& overflow);
void OutputNumber(char[], char[], char[]);

int main() {
	int size, numDigits1, numDigits2;
	char digits1[SIZE];
	char digits2[SIZE];
	char sum[SIZE];
	char repeatAnswer;
	
	do{
		InitNumber(digits1, digits2, size, size);
		AddArrays(digits1, digits2, sum, overflow);
		if(overflow != 'y'){
			OutputNumber(digits1, digits2, sum);
		}
		
		cout << "\nWould you like to add two more numbers (y/n)? ";
		cin >> repeatAnswer;
	}
	while(repeatAnswer == 'y');
}

void InitNumber(char digits1[], char digits2[], int numDigits1, int numDigits2){
	int i;
	
	cout << "Please enter your first number\n" << "How many digits are in your number? ";
	cin >> numDigits1;
	
	//A loop continues until the user has input the total number of digits specified before
	cout << "Please enter your number starting with the LEAST significant digit: ";
	for(i = SIZE-1; i >= SIZE - numDigits1; i--) {
		cin >> digits1[i];
	}
	
	//Stores a 0 in each of the remaining spots of the array
	for(i = SIZE - numDigits1 - 1; i >= 0; i--) {
		digits1[i] = '0';
	}
	
	cout << "Please enter your second number\n" << "How many digits are in your number? ";
	cin >> numDigits2;
	
	//A loop continues until the user has input the total number of digits specified before
	cout << "Please enter your number starting with the LEAST significant digit: ";
	for(i = SIZE-1; i >= SIZE - numDigits2; i--) {
		cin >> digits2[i];
	}
	
	//Stores a 0 in each of the remaining spots of the array
	for(i = SIZE - numDigits2 - 1; i >= 0; i--) {
		digits2[i] = '0';
	}
}

void AddArrays(char digits1[], char digits2[], char sum[], char& overflow){
	int i, tempDigits1, tempDigits2, tempSum, tempOne = 0;
	
	for(i = SIZE-1; i >= 0; i--){
		tempDigits1 = digits1[i] - '0';
		tempDigits2 = digits2[i] - '0';
		tempSum = tempDigits1 + tempDigits2 + tempOne;
		if(tempSum >= 10){
			switch(tempSum){
				case 10:
					sum[i] = '0';
					tempOne = 1;
					break;
				case 11:
					sum[i] = '1';
					tempOne = 1;
					break;
				case 12:
					sum[i] = '2';
					tempOne = 1;
					break;
				case 13:
					sum[i] = '3';
					tempOne = 1;
					break;
				case 14:
					sum[i] = '4';
					tempOne = 1;
					break;
				case 15:
					sum[i] = '5';
					tempOne = 1;
					break;
				case 16:
					sum[i] = '6';
					tempOne = 1;
					break;
				case 17:
					sum[i] = '7';
					tempOne = 1;
					break;
				case 18:
					sum[i] = '8';
					tempOne = 1;
					break;
				case 19:
					sum[i] = '9';
					tempOne = 1;
					break;
				default:
					break;
			}
		}
		else{
			sum[i] = (tempDigits1 + tempDigits2 + tempOne) + '0';
			tempOne = 0;
		}
	}
	if((tempDigits1 + tempDigits2 + tempOne) >= 10){
		for(i = 0; i < SIZE; i++) {
			cout << digits1[i];
		}
		cout << " + ";
		for(i = 0; i < SIZE; i++) {
			cout << digits2[i];
		}
		cout << " = ERROR: Addition Overflow\n";
		overflow = 'y';
	}
}

void OutputNumber(char digits1[], char digits2[], char sum[]){
	int i, tempDigits1, tempDigits2;
	
	tempDigits1 = digits1[0] - '0';
	tempDigits2 = digits2[0] - '0';
	
	cout << endl;
	
	for(i = 0; i < SIZE; i++) {
			cout << digits1[i] - '0';
	}
	cout << " + ";
	for(i = 0; i < SIZE; i++) {
		cout << digits2[i];
	}
	cout << " = ";
	for(i = 0; i < SIZE; i++) {
		cout << sum[i];
	}
}

[JLBorges]

void print_number( const char digits[] ) {

    if( digits != nullptr ) { // sanity check

        for( ; *digits != 0 && *digits == '0' ; ++digits ) {;} // skip leading zeroes

        if( *digits == 0 ) std::cout << 0 ; // if the number is all zeroes, print one zero
        else for( ; *digits != 0 ; ++digits ) std::cout << *digits ; // otherwise, print remaining digits
    }
}

void OutputNumber( const char digits1[], const char digits2[], const char sum[] ) {

    std::cout << '\n' ;
    print_number(digits1) ;

    std::cout << " + ";
    print_number(digits2) ;
    
    std::cout << " = ";
    print_number(sum) ;
}

http://coliru.stacked-crooked.com/a/705311821d82057b