How to add Numbers (a program)

[Prosper]

I wanted to write a program that can add numbers. I avoided using built in addition and for loops . I avoided less than and greater than signs. I did use however equal to signs and not equal to signs.

 

If the forum moderators can guarantee this topic won't be lost I will permit them to move it to developer's corner. I notice developer's corner topics fade away.

 

WARNING: Try to avoid the first 2 to 3 digits in the second number unless you're willing to wait for hours or maybe a day.

 

http://codepad.org/FZ1zXFNb

 

#include <iostream>
#include <string>
using namespace std;


unsigned int SymbolToNativeIndex(unsigned char chVal)
{
    unsigned int nVal = 0;
    if (chVal == '0')
    {
        nVal = 0;
    }
    else if (chVal == '1')
    {
        nVal = 1;
    }
    else if (chVal == '2')
    {
        nVal = 2;
    }
    else if (chVal == '3')
    {
        nVal = 3;
    }
    else if (chVal == '4')
    {
        nVal = 4;
    }
    else if (chVal == '5')
    {
        nVal = 5;
    }
    else if (chVal == '6')
    {
        nVal = 6;
    }
    else if (chVal == '7')
    {
        nVal = 7;
    }
    else if (chVal == '8')
    {
        nVal = 8;
    }
    else if (chVal == '9')
    {
        nVal = 9;
    }

    return nVal;
}

unsigned char GetNext(unsigned char chVal)
{
    unsigned char chValB = chVal;

    if (chValB == '0')
    {
        chValB = '1';
    }
    else if (chValB == '1')
    {
        chValB = '2';
    }
    else if (chValB == '2')
    {
        chValB = '3';
    }
    else if (chValB == '3')
    {
        chValB = '4';
    }
    else if (chValB == '4')
    {
        chValB = '5';
    }
    else if (chValB == '5')
    {
        chValB = '6';
    }
    else if (chValB == '6')
    {
        chValB = '7';
    }
    else if (chValB == '7')
    {
        chValB = '8';
    }
    else if (chValB == '8')
    {
        chValB = '9';
    }
    else if (chValB == '9')
    {
        chValB = '0';
    }

    return chValB;
}

unsigned char GetNextDown(unsigned char chVal)
{
    unsigned char chValB = chVal;

    if (chValB == '0')
    {
        chValB = '9';
    }
    else if (chValB == '1')
    {
        chValB = '0';
    }
    else if (chValB == '2')
    {
        chValB = '1';
    }
    else if (chValB == '3')
    {
        chValB = '2';
    }
    else if (chValB == '4')
    {
        chValB = '3';
    }
    else if (chValB == '5')
    {
        chValB = '4';
    }
    else if (chValB == '6')
    {
        chValB = '5';
    }
    else if (chValB == '7')
    {
        chValB = '6';
    }
    else if (chValB == '8')
    {
        chValB = '7';
    }
    else if (chValB == '9')
    {
        chValB = '8';
    }

    return chValB;
}

std::string InitBlankNumber()
{
    std::string strVal;
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    return strVal;
}

// numbers must be of fixed size 10 characters
// 0000000000 to 9999999999 (expected input range)


std::string GetNextNumber(std::string strNumber)
{
    std::string strVal;
    strVal = InitBlankNumber();
    unsigned char chIndex = '9';

    if (strNumber[SymbolToNativeIndex(chIndex)] != '9')
    {

        strVal[SymbolToNativeIndex(chIndex)] = GetNext(strNumber[SymbolToNativeIndex(chIndex)]);
        chIndex = GetNextDown(chIndex);

        while (chIndex != '0')
        {
            strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];
            chIndex = GetNextDown(chIndex);
        }

        strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];


    }
    else if (strNumber[SymbolToNativeIndex(chIndex)] == '9')
    {

        strVal[SymbolToNativeIndex(chIndex)] = '0';
        chIndex = GetNextDown(chIndex);

        bool bStillNine = true;
        while (bStillNine == true)
        {
            bStillNine = (strNumber[SymbolToNativeIndex(chIndex)] == '9');
            if (bStillNine == true)
            {
                strVal[SymbolToNativeIndex(chIndex)] = '0';
            }
            else
            {
                strVal[SymbolToNativeIndex(chIndex)] = GetNext(strNumber[SymbolToNativeIndex(chIndex)]);
                chIndex = GetNextDown(chIndex);
                bStillNine = false;
                break;
            }

            chIndex = GetNextDown(chIndex);
            if (chIndex == '0' && bStillNine == true)
            {
                if (strNumber[SymbolToNativeIndex(chIndex)] == '9')
                {
                    strVal[SymbolToNativeIndex(chIndex)] = '0';
                }
                else
                {
                    bStillNine = false;
                }

                break;
            }
        }

        while (chIndex != '0')
        {
            strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];
            chIndex = GetNextDown(chIndex);
        }

        if (chIndex == '0' && bStillNine == false)
        {
            strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];
        }

    }

    return strVal;
}

std::string AddNumberToNumber(std::string l, std::string r)
{
    std::string strResult = l;

    std::string strCounter = InitBlankNumber();

    while (strCounter != r)
    {
        strResult = GetNextNumber(strResult);
        strCounter = GetNextNumber(strCounter);
    }

    return strResult;
}



std::string GetInput();
void Test();

int main()
{
    Test();
    return 0;
}

std::string GetInput()
{
    std::string strInput;
    getline(cin, strInput);
    return strInput;
}

void Test()
{

    while (true)
    {

        cout << "Input value A: " << endl;
        std::string strA = GetInput();
        if (strA.size() != 10)
        {
            strA = InitBlankNumber();
            cout << "Number should only be length of 10. Value will be default of: " << InitBlankNumber() << endl;
        }

        cout << "Input value B: " << endl;
        std::string strB = GetInput();
        if (strB.size() != 10)
        {
            strB = InitBlankNumber();
            cout << "Number should only be length of 10. Value will be default of: " << InitBlankNumber() << endl;
        }

        cout << AddNumberToNumber(strA, strB) << endl;

        cout << "Press q to quit otherwise input something else to continue." << endl;
        if (GetInput() == "q")
        {
            break;
        }
    }


    cout << "Any key plus enter to exit." << endl;
    GetInput();
}

Edited January 11, 2014 by Prosper

[IndiraLightfoot]

 

#include<iostream>
#include <conio.h>
using namespace std;
main()
{
int a,b,c;
cout<<"Enter two numbers"<<endl;
cin>>a>>b;
c=a+b;
cout<<"Sum of two numbers are"<<c;
cout<<c<<endl;
getch();
}

[Prosper]

For multiplication. Multiplication of course can be even slower if you pick high enough values.

 

 

http://codepad.org/fd1ijnze

 

 

#include <iostream>
#include <string>
using namespace std;


unsigned int SymbolToNativeIndex(unsigned char chVal)
{
    unsigned int nVal = 0;
    if (chVal == '0')
    {
        nVal = 0;
    }
    else if (chVal == '1')
    {
        nVal = 1;
    }
    else if (chVal == '2')
    {
        nVal = 2;
    }
    else if (chVal == '3')
    {
        nVal = 3;
    }
    else if (chVal == '4')
    {
        nVal = 4;
    }
    else if (chVal == '5')
    {
        nVal = 5;
    }
    else if (chVal == '6')
    {
        nVal = 6;
    }
    else if (chVal == '7')
    {
        nVal = 7;
    }
    else if (chVal == '8')
    {
        nVal = 8;
    }
    else if (chVal == '9')
    {
        nVal = 9;
    }

    return nVal;
}

unsigned char GetNext(unsigned char chVal)
{
    unsigned char chValB = chVal;

    if (chValB == '0')
    {
        chValB = '1';
    }
    else if (chValB == '1')
    {
        chValB = '2';
    }
    else if (chValB == '2')
    {
        chValB = '3';
    }
    else if (chValB == '3')
    {
        chValB = '4';
    }
    else if (chValB == '4')
    {
        chValB = '5';
    }
    else if (chValB == '5')
    {
        chValB = '6';
    }
    else if (chValB == '6')
    {
        chValB = '7';
    }
    else if (chValB == '7')
    {
        chValB = '8';
    }
    else if (chValB == '8')
    {
        chValB = '9';
    }
    else if (chValB == '9')
    {
        chValB = '0';
    }

    return chValB;
}

unsigned char GetNextDown(unsigned char chVal)
{
    unsigned char chValB = chVal;

    if (chValB == '0')
    {
        chValB = '9';
    }
    else if (chValB == '1')
    {
        chValB = '0';
    }
    else if (chValB == '2')
    {
        chValB = '1';
    }
    else if (chValB == '3')
    {
        chValB = '2';
    }
    else if (chValB == '4')
    {
        chValB = '3';
    }
    else if (chValB == '5')
    {
        chValB = '4';
    }
    else if (chValB == '6')
    {
        chValB = '5';
    }
    else if (chValB == '7')
    {
        chValB = '6';
    }
    else if (chValB == '8')
    {
        chValB = '7';
    }
    else if (chValB == '9')
    {
        chValB = '8';
    }

    return chValB;
}

std::string InitBlankNumber()
{
    std::string strVal;
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    strVal.push_back('0');
    return strVal;
}

// numbers must be of fixed size 10 characters
// 0000000000 to 9999999999 (expected input range)


std::string GetNextNumber(std::string strNumber)
{
    std::string strVal;
    strVal = InitBlankNumber();
    unsigned char chIndex = '9';

    if (strNumber[SymbolToNativeIndex(chIndex)] != '9')
    {

        strVal[SymbolToNativeIndex(chIndex)] = GetNext(strNumber[SymbolToNativeIndex(chIndex)]);
        chIndex = GetNextDown(chIndex);

        while (chIndex != '0')
        {
            strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];
            chIndex = GetNextDown(chIndex);
        }

        strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];


    }
    else if (strNumber[SymbolToNativeIndex(chIndex)] == '9')
    {

        strVal[SymbolToNativeIndex(chIndex)] = '0';
        chIndex = GetNextDown(chIndex);

        bool bStillNine = true;
        while (bStillNine == true)
        {
            bStillNine = (strNumber[SymbolToNativeIndex(chIndex)] == '9');
            if (bStillNine == true)
            {
                strVal[SymbolToNativeIndex(chIndex)] = '0';
            }
            else
            {
                strVal[SymbolToNativeIndex(chIndex)] = GetNext(strNumber[SymbolToNativeIndex(chIndex)]);
                chIndex = GetNextDown(chIndex);
                bStillNine = false;
                break;
            }

            chIndex = GetNextDown(chIndex);
            if (chIndex == '0' && bStillNine == true)
            {
                if (strNumber[SymbolToNativeIndex(chIndex)] == '9')
                {
                    strVal[SymbolToNativeIndex(chIndex)] = '0';
                }
                else
                {
                    bStillNine = false;
                }

                break;
            }
        }

        while (chIndex != '0')
        {
            strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];
            chIndex = GetNextDown(chIndex);
        }

        if (chIndex == '0' && bStillNine == false)
        {
            strVal[SymbolToNativeIndex(chIndex)] = strNumber[SymbolToNativeIndex(chIndex)];
        }

    }

    return strVal;
}

std::string AddNumberToNumber(std::string l, std::string r)
{
    std::string strResult = l;

    std::string strCounter = InitBlankNumber();

    while (strCounter != r)
    {
        strResult = GetNextNumber(strResult);
        strCounter = GetNextNumber(strCounter);
    }

    return strResult;
}

std::string MultiplyNumberByNumber(std::string l, std::string r)
{
    std::string strResult = InitBlankNumber();

    std::string strCounter = InitBlankNumber();

    while (strCounter != r)
    {

        strResult = AddNumberToNumber(strResult, l);
        strCounter = GetNextNumber(strCounter);
    }

    return strResult;

}


std::string GetInput();
void Test();

int main()
{
    Test();
    return 0;
}

std::string GetInput()
{
    std::string strInput;
    getline(cin, strInput);
    return strInput;
}

void Test()
{

    while (true)
    {

        cout << "Input value A: " << endl;
        std::string strA = GetInput();
        if (strA.size() != 10)
        {
            strA = InitBlankNumber();
            cout << "Number should only be length of 10. Value will be default of: " << InitBlankNumber() << endl;
        }

        cout << "Input value B: " << endl;
        std::string strB = GetInput();
        if (strB.size() != 10)
        {
            strB = InitBlankNumber();
            cout << "Number should only be length of 10. Value will be default of: " << InitBlankNumber() << endl;
        }

        //cout << AddNumberToNumber(strA, strB) << endl;
        cout << MultiplyNumberByNumber(strA, strB) << endl;

        cout << "Press q to quit otherwise input something else to continue." << endl;
        if (GetInput() == "q")
        {
            break;
        }
    }


    cout << "Any key plus enter to exit." << endl;
    GetInput();
}

Edited January 11, 2014 by Prosper

[sorophx]

#include<iostream>
using std::cout;
using std::cin;
using std::endl;
main(){
int a,b;
cout<<"Enter two numbers"<<endl;
cin>>a>>b;
cout<<"Sum of two numbers is: "<< a + b <<endl;
system("PAUSE");
}

fixed   

Prosper did say "avoid + sign", so you don't get a cookie, I'm afraid 

Edited January 11, 2014 by sorophx

[IndiraLightfoot]

Prosper: I draw my gun before even reading your post correctly, it seems! Sorry.

 

sorophx: Yup! One include had to go then, and then cue system("PAUSE"); Thank you, or should I say, Kiitos!

[rjshae]

Would it work better with 2D arrays? I.e. adding 3 and 2 => result in array element [3][2].

[sorophx]

logical operations are the way to go

[Prosper]

This removes and replaces std::string with my own.

 

http://codepad.org/AWPaMm6U

http://codepad.org/xuRpWhkr (slight update, I make sure a null terminator is set after input is grabbed)

Edited January 12, 2014 by Prosper

[alanschu]

While in practice you'd never do it this way, it's actually an interesting exercise in terms of getting practice.

 

I probably would use a switch statement as, for whatever reason, I find them more pleasing to look at than a series of if-else-if statements.

 

 

Note that a line such as the following:

else if (strNumber[SymbolToNativeIndex(chIndex)] == '9')

Given that your first if statement checks the entire space that is mutually exclusive from this, you don't need to perform the logical check here.

 

 

A useful exercise would be to look over the code and determine, specifically, why it's so slow with particularly large numbers and to see if there's any way you could improve upon the existing code to speed it up (potentially a lot).