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Looping problem

Rashad2 (57)
Im having a problem with my loop. If someone gives me a credit card number less then 13 or greater than 16, i want it to loop and ask the user to enter a new number. It doesnt do that. Its on line 92 til 95
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#include<iostream>
#include<sstream>
#include<string>
#include<cmath>

using namespace std;

//Method for check first numbers in string
bool creditCardType(string cardNumber)
{

    return
    //For Visa cards
    (cardNumber.compare(0, 1, "4") == 0) ||
    //For Mastercards
    (cardNumber.compare(0, 1, "5") == 0) ||
    //For American Express card
    (cardNumber.compare(0, 2, "37") == 0) ||
    //For Discover cards
    (cardNumber.compare(0, 1, "6") == 0);
    
}
//Create a method called getdigit which keeps adding
//Numbers for credit card validation.
int getDigit(int number)
{
    int result =0;
    while(number)
    {
        result = result + (number%10);
        number = number/10;
    }
    return result;
}
// to calculate sum of numbers at even places.
int sumOfDoubleEvenPlaces(const string& cardNumber)
{
    int sum_even_places = 0;
    for (int i = cardNumber.length() -2; i>=0; i-=2)
    {
        sum_even_places = sum_even_places + getDigit(2*(cardNumber[i] - '0'));
    }
    return sum_even_places;
}
//to calculate sum of numbers at odd places.
int sumofoddplace(const string& cardNumber)
{
    int sumoddplaces = 0;
    for (int i = cardNumber.length() -1; i>=0; i-=2)
    {
        sumoddplaces = sumoddplaces +((cardNumber[i] - '0'));
    }
    return sumoddplaces;
}

// function to check card is valid or not.
bool isValid(const string& cardNumber)
{
    return ((sumOfDoubleEvenPlaces(cardNumber)+sumofoddplace(cardNumber))%10==0);
}

//Write a program that asks the user for a credit card number.
//Execute using conditions below.
int main()
{
    long int cardnNum;
    int choice;
    //Enter credit card number.
    cout << "Please enter your credit card number: ";
    cin >>cardnNum;
    cout << endl;
    stringstream ss;
    ss << cardnNum;
    string cardnumber = ss.str();
    // 1= use asset logic on length of credit card number
    cout <<"Press 1 to use asset logic on length of credit card number" << endl;
    // 2= print error message and continue on to next credit card number.
    cout <<"Press 2 to use creditCardType logic on credit card number " << endl;
    cin >> choice;
    if(choice == 1)
    {
        cout << cardnumber << " is a ";
        if(cardnumber[0] == '4')
            cout <<" VISA";
        if(cardnumber[0] == '5')
            cout <<" MASTER";
        if(cardnumber[0] == '6')
            cout <<" DISCOVER";
        if(cardnumber[0] == '3')
            cout <<" AMERICAN EXPRESS";
        cout << endl;
        do{{
        if((cardnumber.length()>=13 && cardnumber.length()<=16))
            cout << cardnumber << " has a length of " <<cardnumber.length() <<" is a valid card " << endl;
        }while((cardnumber[0]>=13)&&(cardnumber[0]<=16));
        else
        {
        cout << cardnumber<< " has a length of " <<cardnumber.length() <<" is an invalid card " << endl;
        }
    else if(choice == 2)
    {
        if(creditCardType(cardnumber) && isValid(cardnumber))
        {
            cout << cardnumber << " is a ";
            if(cardnumber[0] == '4')
                cout <<" VISA";
            if(cardnumber[0] == '5')
                cout <<" MASTER";
            if(cardnumber[0] == '6')
                cout <<" DISCOVER";
            if(cardnumber[0] == '3')
                cout <<" AMERICAN EXPRESS";
            cout <<" Is Valid card " << endl;
        }
        cout << cardnumber << " has invalid type so "<< cardnumber<<" is an invalid card " << endl;
        return 0;
    }}
lsk (141)
in while you decide what condition that make your program won't go out of loop. Must be condition You do not want.

while((cardnumber.length()<13)||(cardnumber.length()>16));
Last edited on
Rashad2 (57)
Thanks but it didnt solve my issue. I actual need it to ask the user to ask the first question again on line 69 which i just realized was my mistake. What i want it to do is if the user enters a length shorter than 13 or longer than 16 to ask the question again. Here is the up to date code. 
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#include<iostream>
#include<sstream>
#include<string>
#include<cmath>

using namespace std;

//Method for check first numbers in string
bool creditCardType(string cardNumber)
{
    
    return
    //For Visa cards
    (cardNumber.compare(0, 1, "4") == 0) ||
    //For Mastercards
    (cardNumber.compare(0, 1, "5") == 0) ||
    //For American Express card
    (cardNumber.compare(0, 2, "37") == 0) ||
    //For Discover cards
    (cardNumber.compare(0, 1, "6") == 0);
    
}

int getDigit(int number)
{
    int result =0;
    while(number)
    {
        result = result + (number%10);
        number = number/10;
    }
    return result;
}

// to calculate sum of numbers at even places.
int sumOfDoubleEvenPlaces(const string& cardNumber)
{
    int sum_even_places = 0;
    for (int i = cardNumber.length() -2; i>=0; i-=2)
    {
        sum_even_places = sum_even_places + getDigit(2*(cardNumber[i] - '0'));
    }
    return sum_even_places;
}

//to calculate sum of numbers at odd places.
int sumofoddplace(const string& cardNumber)
{
    int sumoddplaces = 0;
    for (int i = cardNumber.length() -1; i>=0; i-=2)
    {
        sumoddplaces = sumoddplaces +((cardNumber[i] - '0'));
    }
    return sumoddplaces;
}

// function to check card is valid or not. Should get sumofdoubleven and sumofoddplaces.
bool isValid(const string& cardNumber)
{
    return ((sumOfDoubleEvenPlaces(cardNumber)+sumofoddplace(cardNumber))%10==0);
}

//Write a program that asks the user for a credit card number.
//Execute using conditions below. 7/18
int main()
{
    long int cardnNum;
    int choice;
    do{
    //Enter credit card number.
    cout << "Please enter your credit card number: ";
    cin >>cardnNum;
    }while((cardnNum.length()<13)||(cardnNum.length()>16));
    cout << endl;
    
    stringstream ss;
    ss << cardnNum;
    string cardnumber = ss.str();
    
    // 1= use asset logic on length of credit card number
    cout <<"Press 1 to use asset logic on length of credit card number" << endl;
    
    // 2= print error message and continue on to next credit card number.
    cout <<"Press 2 to use creditCardType logic on credit card number " << endl;
    cin >> choice;
    
    //If choice 1, use assert logic.
    if(choice == 1)
    {
        cout << cardnumber << " is a ";
        if(cardnumber[0] == '4')
            cout <<" VISA";
        if(cardnumber[0] == '5')
            cout <<" MASTER";
        if(cardnumber[0] == '6')
            cout <<" DISCOVER";
        if(cardnumber[0] == '3')
            cout <<" AMERICAN EXPRESS";
        cout << endl;
        
            if((cardnumber.length()>=13 && cardnumber.length()<=16))
                cout << cardnumber << " has a length of " <<cardnumber.length() <<" is a valid card " << endl;
            else
                cout << cardnumber<< " has a length of " <<cardnumber.length() <<" is an invalid card " << endl;
    }
    else if(choice == 2)
    {
        if(creditCardType(cardnumber) && isValid(cardnumber))
        {
            cout << cardnumber << " is a ";
            if(cardnumber[0] == '4')
                cout <<" VISA";
            if(cardnumber[0] == '5')
                cout <<" MASTER";
            if(cardnumber[0] == '6')
                cout <<" DISCOVER";
            if(cardnumber[0] == '3')
                cout <<" AMERICAN EXPRESS";
            cout <<" Is Valid card " << endl;
        }
        cout << cardnumber << " has invalid type so "<< cardnumber<<" is an invalid card " << endl;
        system("pause");
        return 0;
    }}
lsk (141)
Sorry my mistake, I saw you use cardnNum.length() so I suggest that condition.(But that condition still good to use)

Now I saw you used long int cardnNum;, the .length() is for string.

Change long int cardnNum; to be string cardnNum;?
I saw your code use cardnNum like a string more than a long.
Last edited on
Rashad2 (57)
Thanks for the help. Appreciate it. I hate not seeing those simple mistakes
lsk (141)
Just an experience from facing too many errors before, LOL.
Last edited on
Rashad2 (57)
I came across another error now. It will loop for both valid and invalid so if i put a number less than 13 and greater than 16 it loops but also does the same for valid entries. 
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#include<iostream>
#include<sstream>
#include<string>
#include<cmath>

using namespace std;

//Method for check first numbers in string
bool creditCardType(string cardNumber)
{
    
    return
    //For Visa cards
    (cardNumber.compare(0, 1, "4") == 0) ||
    //For Mastercards
    (cardNumber.compare(0, 1, "5") == 0) ||
    //For American Express card
    (cardNumber.compare(0, 2, "37") == 0) ||
    //For Discover cards
    (cardNumber.compare(0, 1, "6") == 0);
    
}

int getDigit(int number)
{
    int result =0;
    while(number)
    {
        result = result + (number%10);
        number = number/10;
    }
    return result;
}

// to calculate sum of numbers at even places.
int sumOfDoubleEvenPlaces(const string& cardNumber)
{
    int sum_even_places = 0;
    for (int i = cardNumber.length() -2; i>=0; i-=2)
    {
        sum_even_places = sum_even_places + getDigit(2*(cardNumber[i] - '0'));
    }
    return sum_even_places;
}

//to calculate sum of numbers at odd places.
int sumofoddplace(const string& cardNumber)
{
    int sumoddplaces = 0;
    for (int i = cardNumber.length() -1; i>=0; i-=2)
    {
        sumoddplaces = sumoddplaces +((cardNumber[i] - '0'));
    }
    return sumoddplaces;
}

// function to check card is valid or not. Should get sumofdoubleven and sumofoddplaces.
bool isValid(const string& cardNumber)
{
    return ((sumOfDoubleEvenPlaces(cardNumber)+sumofoddplace(cardNumber))%10==0);
}

//Write a program that asks the user for a credit card number.
//Execute using conditions below. 7/18
int main()
{
    string cardnNum;
    int choice;
    do{
    //Enter credit card number.
    cout << "Please enter your credit card number: ";
    cin >>cardnNum;
    }while((cardnNum.length()<13)||(cardnNum.length()>16));
    cout << endl;
    
    stringstream ss;
    ss << cardnNum;
    string cardnumber = ss.str();
    
    // 1= use asset logic on length of credit card number
    cout <<"Press 1 to use asset logic on length of credit card number" << endl;
    
    // 2= print error message and continue on to next credit card number.
    cout <<"Press 2 to use creditCardType logic on credit card number " << endl;
    cin >> choice;
    
    //If choice 1, use assert logic.
    if(choice == 1)
    {
        cout << cardnumber << " is a ";
        if(cardnumber[0] == '4')
            cout <<" VISA";
        if(cardnumber[0] == '5')
            cout <<" MASTER";
        if(cardnumber[0] == '6')
            cout <<" DISCOVER";
        if(cardnumber[0] == '3')
            cout <<" AMERICAN EXPRESS";
        cout << endl;
        
            if((cardnumber.length()>=13 && cardnumber.length()<=16))
                cout << cardnumber << " has a length of " <<cardnumber.length() <<" is a valid card " << endl;
            else
                cout << cardnumber<< " has a length of " <<cardnumber.length() <<" is an invalid card " << endl;
    }
    else if(choice == 2)
    {
        if(creditCardType(cardnumber) && isValid(cardnumber))
        {
            cout << cardnumber << " is a ";
            if(cardnumber[0] == '4')
                cout <<" VISA";
            if(cardnumber[0] == '5')
                cout <<" MASTER";
            if(cardnumber[0] == '6')
                cout <<" DISCOVER";
            if(cardnumber[0] == '3')
                cout <<" AMERICAN EXPRESS";
            cout <<" Is Valid card " << endl;
        }
        cout << cardnumber << " has invalid type so "<< cardnumber<<" is an invalid card " << endl;
        system("pause");
        return 0;
    }}
lsk (141)
Could you give me an example of your input and your result?
I don't face that problem.
Rashad2 (57)
If i put 31234567 that 8 so it should ask again if i put3123456789123 its between 13 and 16 so it shouldnt loop.
Rashad2 (57)
Maybe its just my compiler? I use Xcode.
lsk (141)
For me 3123456789123 doesn't get back to the loop.
Are you sure you entered right?
Which IDE you're using?

Maybe, but that doesn't make sense.
try cout << cardnumber.length();
Last edited on
Rashad2 (57)
I just ran it on shell instead and it didnt happen so im not worried about it.
lsk (141)
Okay,

but this issue's gonna stuck in my head for a while.
Maybe I have to find someway to try Xcode, LOL.
Rashad2 (57)
Well ill try and post a screen shot.
Rashad2 (57)
Ok what happened now was that quit Xcode and then reopened it and pasted the code. Now it runs just the way it should. Thats really weird. Now i Cant get that screen shot. I dont know why that happened. I guess its a wierd compiler lol
lsk (141)
Weird, too.
I won't use it I promise, lol.
xenovia12 (658)
i didnt read you whole code just the line you said.. i think becuase do while has a 2 first bracket
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