#include<stdio.h>
#include<string.h>
#include<math.h>
int hexadecimal_decimal(char hex[100])
{
    int i = 0, val,decimal,len;
    decimal = 0;
    len = strlen(hex);
    len--;
    for(i=0; hex[i]!='\0'; i++)
    {
        if(hex[i]>='0' && hex[i]<='9')
        {
            val = hex[i] - 48;
        }
        else if(hex[i]>='a' && hex[i]<='f')
        {
            val = hex[i] - 97 + 10;
        }
        else if(hex[i]>='A' && hex[i]<='F')
        {
            val = hex[i] - 65 + 10;
        }

        decimal += val * pow(16, len);
        len--;

    }
    return decimal;

}

int  octaldecimal(int c)
{
    int temp=0,i=0,mod;
    while(c!=0)
    {
        mod=c%10;
        temp=temp+mod*pow(8,i);
        c=c/10;
        i++;
    }
    return temp;
}


int  decimal(int c)
{
    int temp=0,i=0,mod;
    while(c!=0)
    {
        mod=c%10;
        temp=temp+mod*pow(2,i);
        c=c/10;
        i++;
    }
    return temp;
}

void hexadecimal(int a)
{
    int  i=0,count=0,arr[1000];
    while(a!=0)
    {
        arr[i]=a%16;
        count+=1;
        a=a/16;
        if(arr[i]<10)
        {
            arr[i]=48+arr[i];
        }
        else if(arr[i]>=10)
        {
            arr[i]=55+arr[i];
        }
        i++;

    }
    for(i=count-1; i>=0; i--)
    {
        printf("%c",arr[i]);
    }
}


void binary(int c)
{
    int count=0,i=0,arr[1000];
    while(c!=0)
    {
        arr[i]=c%2;
        count+=1;
        c=c/2;
        i++;
    }
    for(i=count-1; i>=0; i--)
    {
        printf("%d",arr[i]);
    }
}


int main()
{
    int a,b,c,x,z,j,k;
    char st[9];
    printf("                                             Welcome                                                   \n");
    printf("                                      This is our menu bar                              \n");
    printf(" \n");

        printf("//Enter 1   for Decimal to Binary      :\t      //Enter 2   for Octal to Binary       :\n");
        printf("//Enter 3   for Decimal to Octal       :\t      //Enter 4   for Octal to Decimal      :\n");
        printf("//Enter 5   for Decimal to Hexadesimal :\t      //Enter 6   for Octal to Hexadesimal  :\n");
        printf("                                        \t                                             \n");
        printf("                                        \t                                             \n");
        printf("//Enter 7   for Binary  to Decimal     :\t      //Enter 8   for Hexadesimal to Decimal:\n");
        printf("//Enter 9   for Binary  to Octal       :\t      //Enter 10  for Hexadesimal to Binary :\n");
        printf("//Enter 11  for Binary  to Hexadesimal :\t      //Enter 12  for Hexadesimal to Octal  :\n");
        printf("                                                                                       \n");


        for(k=0; ; k++)
        {
            printf("\n");
            printf("****Enter your number:  ");
            scanf("%d",&b);
            printf("\n");

            if(b==1)
            {
                printf("Enter Decimal number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                printf("The Binary from of %d is :\n",c);
                printf("                         \n");
                binary(c);
                printf("                         \n");
            }
            else if(b==2)
            {
                printf("Enter Octal number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                x=octaldecimal(c);
                printf("The Binary from of Octal number is: ");
                binary(x);
                printf("                         \n");
            }

            else if(b==3)
            {
                printf("Enter Decimal number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                printf("The Octal from of Decimal number is: %o\n",c);
                printf("                         \n");
            }

            else if(b==4)
            {
                printf("Enter Octal number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                x=octaldecimal(c);
                printf("The Decimal from of Octal number is: %d",x);
                printf("                         \n");
            }

            else if(b==5)
            {
                printf("Enter Decimal number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                printf("The Hexadecimal from of Decimal number is: ");
                hexadecimal(c);
                printf("                         \n");
            }

            else if(b==6)
            {
                printf("Enter Octal number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                x=octaldecimal(c);
                printf("The Hexadecimal from of Octal number is: ");
                hexadecimal(x);
                printf("                         \n");

            }

            else if(b==7)
            {
                printf("Enter Binary number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                printf("The Decimal from of Binary number is: %d\n",decimal(c));
                printf("                         \n");

            }
            else if(b==8)
            {
                printf("Enter Hexadecimal number:\n");
                printf("                         \n");
                char str[100];
                scanf("%s",str);
                printf("                         \n");
                x=hexadecimal_decimal(str);
                printf("The Decimal from of hexadecimal is: %d",x);
                printf("                         \n");
            }

            else if(b==9)
            {
                printf("Enter Binary number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                x=decimal(c);
                printf("The Octal from of Binary number is: %o\n",x);
                printf("                         \n");
            }
            else if(b==10)
            {
                printf("Enter Hexadecimal number:\n");
                printf("                         \n");
                char str[100];
                scanf("%s",str);
                printf("                         \n");
                x=hexadecimal_decimal(str);
                printf("The Binary from of Hexadecimal number is :\n");
                printf("                         \n");
                binary(x);
                printf("                         \n");


            }
            else if(b==11)
            {
                printf("Enter Binary number:\n");
                printf("                         \n");
                scanf("%d",&c);
                printf("                         \n");
                x=decimal(c);
                printf("The Hexadecimal from of Binary number is: ");
                hexadecimal(x);
                printf("                         \n");
            }
            else if(b==12)
            {
                printf("Enter Hexadecimal number:\n");
                printf("                         \n");
                char str[100];
                scanf("%s",str);
                printf("                         \n");
                x=hexadecimal_decimal(str);
                printf("The Octal from of Hexadecimal number is: %o",x);
                printf("                         \n");

            }
            printf("\n");
            printf("                                                    For continue write 'c'-                                    \n");
            printf("\n");
            printf("                                                     For exit write 'e'-                                      \n");
            printf("\n");
            scanf("%s",st);
            if(st[0]=='e')
            {
                break;
            }
            else if(st[0]=='c')
            {
                continue;
            }
        }




    return 0;

}