[FIXED] How to convert hexadecimal to decimal in C?

Issue

So, with my beginner level of experience in C I've been trying to write a code that converts hexadecimal input to a decimal with an array. I believe you will get it more spesificly by looking at my code but it does not work properly. I keep getting an amount that is much larger than intended.

#include <stdio.h>

int main()
{


    int i, k, j, N, power, result;

    char array[50];

    result = 0;

    printf("how many charecters are there in your hexadecimal input?: \n");
    scanf("%d", &N);

    for(k=0; k<=N-1; k++)
    {
        printf("What is the %d . value of your hexadecimal input?: \n", k+1);
        scanf("%s", &array[k]);
    }


    for(i=0; i<=N-1; i++)
    {
        power = 1;
        for(j=0; j<=i; j++)
        {
        
            power = power *16;
        }
    
        if((array[i] >= 0) && (array[i] <= 9))
        {
            result = result + array[i] * power;
        
        }
    
        else
        {
            result = result + (array[i] - 'A' + 10) * power;
        }
    }   


    printf("your result is %d", result);

    return 0;
    

}

Solution

just edited your code a little bit, and also the input is supposed to be from left to right instead of right to left according to which I think you have coded. Hence, for C6, first C then 6.

#include <stdio.h>

int main()
{


    int i, k, j, N, power, result;

    char array[50];

    result = 0;

    printf("how many charecters are there in your hexadecimal input?: \n");
    scanf("%d", &N);

    for(k=0; k<=N-1; k++)
    {
        printf("What is the %d . value of your hexadecimal input?: \n", k+1);
        scanf(" %c", &array[k]);
    }


    for(i=0; i<=N-1; i++)
    {
        power = 1;
        
        for(j=0; j<=N-2-i; j++)
        {
            power = power*16;
        }
        
        if((array[i] >= '0') && (array[i] <= '9'))
        {
            result = result + (array[i] - '0') * power;
        
        }
    
        else
        {
            result = result + (array[i] - 'A' + 10) * power;
        }
    }   


    printf("your result is %d", result);

    return 0;
    
}

the takeaways

1. your input taking is inefficeient. and in that too %c instead of %s in scanf.
2. if((array[i] >= 0) && (array[i] <= 9)), suppose i=1 and array[1] = 7. Now, you are comparing ascii value of 7 which is 55, instead of 7.
3. same thing in the statement of if, the ascii values of array[i] are being used so I have subtracted accordingly.

Answered By - mr.loop

Answer Checked By - Mildred Charles (PHPFixing Admin)