For some reason the program is not working when I try to run it and I can't figure it out. I'd appricate any help. Homework stuff, so I have to stick to the very basics.

#include <stdio.h>
long long int decimal(long long int);
int power_2 (int);
long int power_10 (int);

int main(void){
    long long int n;
    while(1){
        printf("Write down a binary number. \n");
        scanf("%lld", &n);
    long long int a = decimal(n);
    printf("The binary number %lld converted into decimal is: %lld \n", n, a);
    }
    
}

//Here what I realized is if let's say I have the number 1001, then I subtract 1 and divide by 10, the remainder is going to be 0, meaning it will "jump" on the second if statement. I don't really know how to solve it.

long long int decimal(long long int e){
    long long int result;
    long long int k = 0;
    int i;
    for(i=0; i>=0; i  ){
        if(e % 10 == 1){
            k  = power_2(i);
            e--;
            if(e != 0){
            e /= 10;
            }
        }
        if(e % 10 == 0){
            e /= 10;
        if(e==0){
            break;
        }
    }
    return(k);
}

//This function should work, so it's not a problem

int power_2(int n){
    int base = 2, i, result = 1;
    if(n>0){
        for(i=1; i<=n; i  ){
            result *= base;
        }
    }
    if(n=0){
        result = 1;
    }
    return(result);
}

//This is just something I thought I would need but no

long int power_10(int n){
    int base = 10, i, result = 1;
    if(n>0){
        for(i=1; i<=n; i  ){
            result *= base;
        }
    }
    if(n=0){
        result = 1;
    }
    return(result);
}

CodePudding user response：

You can't use scanf with %lld to input a binary number string (e.g. 10101010101010101010101010101010101). It will interpret the number incorrectly.

You have to accept it as a char string (e.g).

char str[100];
scanf("%s",str);

But, scanf is problematic because it can overflow str. And, IMO, the "usual" remedy of:

scanf("