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stoi exception (invalid input)

dakotad8218 (50)
I'm trying to write this program with helper functions that creates a barcode for a 5 digit zip code. This is using a normal 7,4,2,1,0 weighting system. Half bars are denoted by ":" and full bars are denoted by "|" and I have a "|" on either end of the code. I'm getting this exception from the stoi function I used to convert the substr (thought it would be easier to not have to reverse the separated digits as I would have to had done by separating with modulus and division). Does anyone know why?

Error Message: erminate called after throwing an instance of 'std::invalid_argument'
what(): stol


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  #include <iostream>
#include <string>


using namespace std;

/** Converts single digits to barcode fragment strings
 * @param digit (number to be converted)
 * @return bar (barcode fragment)
*/
string digit_to_bar(int digit)
{
    string bar;
    switch(digit)
    {
        case 0: bar = "||:::";
        case 1: bar = ":::||";
        case 2: bar = "::|:|";
        case 3: bar = "::||:";
        case 4: bar = ":|::|";
        case 5: bar = ":|:|:";
        case 6: bar = ":||::";
        case 7: bar = "|:::|";
        case 8: bar = "|::|:";
        case 9: bar = "|:|::";
    }
    return bar;
}



/** Calculates checksum digit of 5 digit zip code
 * @param input (zip code)
 * @return result (number required to reach checksum)
*/
int checksum(int input)
{
    int sum = 0, result = 0;
    while(input > 0)
    {
        sum += input % 10;
        input /= 10;
    }
    while(sum % 10 != 0)
    {
        result++;
        sum++;
    }
    return result;
}

string printBarcode(int zip)
{
        
    /** calculate checksum digit and convert to string */
    string check_digit = to_string(checksum(zip));
    string complete = "| ";
    string digits = to_string(zip);
    for(int i = 0; i <= 5; i++)
    {
        string current = digits.substr(i, 1);
        int k = stoi(current);
        string bar = digit_to_bar(k);
        complete += bar;
    }
    complete += digit_to_bar(checksum(zip)) + " |";
    return complete;
}
/** Main function
 * no paramaters
 * returns 0
*/
int main()
{
    cout << "Enter a ZIP: ";
    int d;
    cin >> d;

    string barcode = printBarcode(d);   

    cout << barcode;

    return 0;
}
salem c (3686)
> for(int i = 0; i <= 5; i++)
This loops 6 times, which isn't good for a 5-digit code,
dakotad8218 (50)
Hmm... well that got it printing something, but it looks like no matter what I enter as the zip code, this is the barcode I end up with:

||:|::|:|::|:|::|:|::|:|::|:|::|

EDIT: added a space between the bar fragments and I was able to figure out it's basically printing the code for 99999. Not sure why
Last edited on
salem c (3686)
Your switch/case in digit_to_bar lacks any break statements.

dakotad8218 (50)
Oh wow... true sign I need to take a break. I must have overlooked that 20 times checking my code. Thank you! Now getting the proper output barcode.
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