problem with if condition

[hamzah150]

this is my code, i am having trouble with my if conditions at the end to make sure that if sum of n1 and n2 is greater than 20 digits it says its invalid. the way i have it now it just gives me invalid right away.

//programmed by hamzah khachiche
#include <iostream>
using namespace std;
#include <string>
#include <cstring>

void read(string n1, string n2, int num1[20], int num2[20], int& a, int& c);
void total(string n1, string n2, int num1[20], int num2[20], int sum[21], int a, int c);

int main()
{
	string n1, n2;
	int a, c;
	int num1[20];
	int num2[20];
	int sum[21];
	read(n1, n2, num1, num2, a, c);
	total(n1, n2, num1, num2, sum, a, c);
	
	return 0;
}

//my function to input the integer and then store it into the array
void read(string n1, string n2, int num1[20], int num2[20], int& a, int& c)
{
	
	
	cout << "Enter the first postive integer of at least 20 digits: " << endl;     //where you enter the first integer
	cin >> n1;
	while (n1.length() > 20)  //this is where you input an integer of 20 digits if you do more than 20 it is invalid and must be redone
	{
		cout << "this is invalid please enter a positive integer of at least 20 digits: " << endl;  
		cin >> n1;
	}
	cout << endl;
	


	cout << "Enter the second postive integer of at least 20 digits: " << endl;  //where you input the second integer
	cin >> n2;
	while (n2.length() > 20)  ////this is where you input an integer of 20 digits if you do more than 20 it is invalid and must be redone
	{
		cout << "this is invalid please enter a positive integer of at least 20 digits: " << endl;
		cin >> n2;
	}
	cout << endl;
	

	int j = 0;  //this is where we are a doing a loop to read the numbers in reverse
	for (int i = n1.length() - 1; i >= 0; i--)
	{
		num1[j] = static_cast<int>(n1[i]) - static_cast<int>('0');  //this then stores the integer into an array
		j++;

	
	}
	a = atoi(n1.c_str()); //this is where i convert the string into an integer

	int k = 0;
	for (int b = n2.length() - 1; b >= 0; b--) //this is the loop for the second set of numbers to store them into reverse
	{
		num2[k] = static_cast<int>(n2[b]) - static_cast<int>('0');  //this stores the second set into an array
		k++;
		
	}
	c = atoi(n2.c_str()); //this is where i convert the second set into an integer
	
}

//this function is where i add the two positive integers
void total(string n1, string n2, int num1[20], int num2[20], int sum[21], int a, int c)
{
	//this first for loop is to add my first set of integers
	int i;
	for (i = 0; i < n1.length(); i++)
	{	
	}
	
	cout << endl;
	//this second for loop is for the second set of integers
	int b;
	for (b = 0; b < n2.length(); b++)
	{ }
	
	int d;
	int h = 2147483647; 
	d = a + c; //this is to add the two integers that where converted into strings
	int q;
	q = (n1.length() + n2.length());
	//these are my if condition statements where i make sure the sum is not greater than h and the sum isnt more than 20 digits
	//this is the part not working, trying to make sure not greater than 20 digits
	if (d > q) //this condition is to make sure the sum of the digits is not greater than 20
	{
		cout << "This is invalid" << endl;
	}
	else if (d > h) //this condition is to make the sum is not greater than 2147483647
		cout << "This is invalid" << endl;
	else
		cout << "the total of " << a << " and " << c << " is: " << d << endl;
	
	
}

[Little Captain]

You're comparing the sum of two integers d = (a + c) and comparing it with
the length of n1 + n2. I've added comments to the appropriate code areas below. (Might be a good idea to format your code using code tags when posting :) )

a = atoi(n1.c_str()); //this is where i convert the string into an integer

c = atoi(n2.c_str()); //this is where i convert the second set into an integer


//(Okay, here you're adding the sum of two integer VALUES)
d = a + c; //this is to add the two integers that where converted into strings

//Here, you're getting the number of characters in each string and summing 
//them
q = (n1.length() + n2.length());

//Now, you're comparing a value against the number of chars in each string
//the result will most likely always be false
if (d > q) 

Let me know if you need more help,

Joe
[e-mail]

[hamzah150]

hi joe,
thanks for answering, and this is my first time using a forum so i didn't know how to make it look neat.

I see what you mean and why it wasn't working, but how can i fix it where i can write a condition that will check and make sure that if the total digits is greater than 20 it will not work but if 20 or less it will work?

[a10e29]

thanks for answering, and this is my first time using a forum so i didn't know how to make it look neat.

http://www.cplusplus.com/articles/jEywvCM9/