Octal_Hexadecimal_without_Function.cpp

#include<iostream>
#include<string.h>
using namespace std;
int main()
{
    int octalNum, rev=0, rem, chk=0, hex=0, mul=1, i=0, k=0;
    char binaryNum[40] = "", hexnum[40];
    cout<<"Enter any Octal Number: ";
    cin>>octalNum;
    while(octalNum!=0)
    {
        rem = octalNum%10;
        if(rem>7)
        {
            chk++;
            break;
        }
        rev = (rev*10) + rem;
        octalNum = octalNum/10;
    }
    if(chk==0)
    {
        octalNum = rev;
        while(octalNum!=0)
        {
            rem = octalNum%10;
            switch(rem)
            {
                case 0: strcat(binaryNum, "000");
                    break;
                case 1: strcat(binaryNum, "001");
                    break;
                case 2: strcat(binaryNum, "010");
                    break;
                case 3: strcat(binaryNum, "011");
                    break;
                case 4: strcat(binaryNum, "100");
                    break;
                case 5: strcat(binaryNum, "101");
                    break;
                case 6: strcat(binaryNum, "110");
                    break;
                case 7: strcat(binaryNum, "111");
                    break;
            }
            octalNum = octalNum/10;
        }
        while(binaryNum[k]!='\0')
            k++;
        chk=1;
        k--;
        while(k>=0)
        {
            if(binaryNum[k]=='0')
                rem = 0;
            else
                rem = 1;
            hex = hex + (rem*mul);
            if(chk%4==0)
            {
                if(hex<10)
                    hexnum[i] = hex+48;
                else
                    hexnum[i] = hex+55;
                mul = 1;
                hex = 0;
                chk = 1;
                i++;
            }
            else
            {
                mul = mul*2;
                chk++;
            }
            k--;
        }
        if(chk!=1)
            hexnum[i] = hex+48;
        if(chk==1)
            i--;
        cout<<"\nEquivalent Hexadecimal Value = ";
        chk = 0;
        for(i=i; i>=0; i--)
        {
            if(hexnum[i]=='0' && chk==0)
            {
                chk++;
                continue;
            }
            else
                cout<<hexnum[i];
        }
    }
    else
        cout<<"\nInvalid Octal Digit "<<rem;
    cout<<endl;
    return 0;
}