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Infinite output when I print a variable inside a loop

jkp993 (2)
I'm trying to convert a number input to words. I am a beginner so my code might look clunky. I also apologise for posting such a large code. The loop at the "String Construction" section crashes and is printing infinite values of the variable q (quotient). I have also tried printing a simple variable like flag = 1 before q and that too is giving infinite 1s. I cannot figure out what is causing this. Any input would be greatly helpful for my learning!

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#include "stdafx.h"
#include <iostream>
#include <string>
#include <cmath>

using namespace std;

int main()
{
int i = 0, number = 0;
string num_name = "";
cout << "Enter a number (maximum value is 1,000,000,000)" << endl;
cin >> number;

//To find the maximum magnitude
while ((number / pow(10, i)) >= 1) 
{
    i++;
}
i--;
int j = i;
cout << j << endl; //Check

//To find which multiple of 3 i is
int n = 0;
while (j >= 3)
{
    if (j % 3 == 0) 
        n++;
    j--;
}
j = i;
cout << j << endl; //Check
cout << n << endl; //Check

//String construction
int k = n;
int q = 0;

while (k >= 1)
    {
    while (j >= (3*k))
    {
        q = (int)(number / pow(10, j));
        if (j == 2 + (3 * k))
        {
            if (q == 1) num_name += "one";
            else if (q == 2) num_name += "two";
            else if (q == 3) num_name += "three";
            else if (q == 4) num_name += "four";
            else if (q == 5) num_name += "five";
            else if (q == 6) num_name += "six";
            else if (q == 7) num_name += "seven";
            else if (q == 8) num_name += "eight";
            else if (q == 9) num_name += "nine";

            num_name += "hundred";
        }
        if (j == 1 + (3 * k)) 
            continue;
        if (j == 3 * k)
        {
            if (q == 1) num_name += "one";
            else if (q == 2) num_name += "two";
            else if (q == 3) num_name += "three";
            else if (q == 4) num_name += "four";
            else if (q == 5) num_name += "five";
            else if (q == 6) num_name += "six";
            else if (q == 7) num_name += "seven";
            else if (q == 8) num_name += "eight";
            else if (q == 9) num_name += "nine";
            else if (q == 10) num_name += "ten";
            else if (q == 11) num_name += "eleven";
            else if (q == 12) num_name += "twelve";
            else if (q == 13) num_name += "thirteen";
            else if (q == 14) num_name += "fourteen";
            else if (q == 15) num_name += "fifteen";
            else if (q == 16) num_name += "sixteen";
            else if (q == 17) num_name += "seventeen";
            else if (q == 18) num_name += "eighteen";
            else if (q == 19) num_name += "nineteen";
            if (q >= 20 && q <= 99)
            {
                int r = 0;
                r = q % 10;
                (int)(q /= 10);
                if (q == 2) num_name += "twenty";
                else if (q == 3) num_name += "thirty";
                else if (q == 4) num_name += "forty";
                else if (q == 5) num_name += "fifty";
                else if (q == 6) num_name += "sixty";
                else if (q == 7) num_name += "seventy";
                else if (q == 8) num_name += "eighty";
                else if (q == 9) num_name += "ninety";

                if (r == 1) num_name += "one";
                else if (r == 2) num_name += "two";
                else if (r == 3) num_name += "three";
                else if (r == 4) num_name += "four";
                else if (r == 5) num_name += "five";
                else if (r == 6) num_name += "six";
                else if (r == 7) num_name += "seven";
                else if (r == 8) num_name += "eight";
                else if (r == 9) num_name += "nine";
        }


            if (k == 3) num_name += "billion";
            else if (k == 2) num_name += "million";
            else if (k == 1) num_name += "thousand";
    }
    number = number % (int)pow(10, j);
    j--;
    }
    k--;
}
cout << num_name << endl;
cin.ignore();
cin.get();
return 0;
}
icy1 (596)
for something like this, wouldn't you rather have a Stack and analyze the number from right to left, pushing words onto the top? 1,234,567

"seven"
"sixty-seven"
"five hundred sixty-seven"
"four thousand five hundred sixty-seven"
"thirty-four thousand five hundred sixty-seven"
"two hundred thirty-four thousand five hundred sixty-seven"
"one million two hundred thirty-four thousand five hundred sixty-seven"

For this same number with your current code, I'm getting i, j, n outputs of 6, 6, 2. Is this expected so far?
ne555 (10692)
> my code might look clunky
proper indentation makes wonders

> cin >> number;
your program ask for input
different inputs may provide different results, so you should gives us an example that does cause the issue.

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	while(k >= 1) {
		while(j >= (3 * k)) {
			q = (int)(number / pow(10, j));
			if(j == 2 + (3 * k)) {
				//...
			}
			if(j == 1 + (3 * k))
				continue; // <---
			//...
		}
		k--;
	}
suppose that you reach the continue line, there is nothing in the code that changes `k' or `j', so the condition of the loop will not modify and then you got an infinete loop
jkp993 (2)
I didn't know I had to include j--; before the continue. And I got to know about switch case just a few moments ago. I'm gonna edit the code to make it more readable by making functions. Thank you all for your help!
Last edited on
icy1 (596)
Hi jkp993,

In case you get curious about std::stack in the future, I think I've got an implementation.

Takeaways:
- avoid doing user input while improving your algorithm; it'll slow you down and you can toss more stuff at it with an array of examples
- try to put reusable strings as const or in const arrays; easier to both reuse and maintain
- comments can help explain unusual bits or variable declarations at a glance

Good luck.

visual representation of number and indices (from right) to show you my approach and pattern
    1, 2 3 4 , 5 6 7
    
i = 6  5 4 3   2 1 0


Stack example:
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#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <vector>

using namespace std;

const string F20[] = {"", "one", "two", "three", "four", "five", "six",
"seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen",
"fifteen", "sixteen", "seventeen", "eighteen", "nineteen"};

const string TENS[] = {"", "", "twenty", "thirty", "forty", "fifty", "sixty",
"seventy", "eighty", "ninety"};

const string HUN = "hundred";

const string THOU[] = {"", "thousand", "million", "billion", "trillion"};

string NumToWords(long n)
{
    if (n==0) { return "zero"; }
    int prev_d = n%10; // Previous digit, esp. for stuff like 'twelve'
    stack<string> st;
    st.push(F20[prev_d]);
    n /= 10;
    
    int d;      // Current digit
    int i = 1;  // Index from the right
    while (n)
    {
        d = n%10;
        if ( i%3 == 0 )  // thousands
        {
            if (d>=1)
            {
                st.push(THOU[i/3]);
                st.push(F20[d]);
            }
        }
        else if ( (i+1)%3 == 0 ) // hundreds
        {
            if (d>=1)
                st.push(F20[d] + " " + HUN);
        }
        else  // tens
        {
            if (d==1)
            {
                st.pop();
                st.push(F20[10+prev_d]);
            }
            else if (d>1)
            {
                st.push(TENS[d] + "-");
            }
        }
        prev_d = d;
        n/=10;
        i+=1;
    }
    
    // Build string, adding space if top doesnt end in a dash
    ostringstream oss;
    while (!st.empty())
    {
        string& top = st.top();
        oss << top;
        if (top.back() != '-')
            oss << ' ';
        st.pop();
    }
    return oss.str();
}

int main()
{
    vector<long> numbers =
    {
        0,
        11,
        33,
        16000,
        1234567,
        1000004,
        1012009,
        1000000000000,
        123000014000200
    };
    for (auto& n : numbers)
        cout << n << ": " << NumToWords(n) << endl;
}


Can test at https://repl.it/repls/LoyalVengefulVaporware

0: zero
11: eleven 
33: thirty-three 
16000: sixteen thousand  
1234567: one million two hundred thirty-four thousand five hundred sixty-seven 
1000004: one million four 
1012009: one million twelve thousand nine 
1000000000000: one trillion  
123000014000200: one hundred twenty-three trillion fourteen million two hundred

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