need help: binary to integer

[P6nn]

Hello!
I have a problem. I have a program, that must convert entered binary number to integer. But this program fails. I have no idea, where should be the mistake.
Please help !
sorry for non englis program - it's in estonian, because my home language is estonian.

#include <stdio.h>
#include <math.h>

void bin_dec();

int main(){
    while(1){
    char otsus;
    //Sissejuhatus ja valik
    printf("Mis teisendust on vaja teha:\n");
    printf("d - kahendsusteemist kumnendsusteemi\n");
    printf("v - välju programmist.\n");
    printf("Teie otsus: ");
    scanf("%s", &otsus);

    if(strcmp(&otsus, "d") == 0){
            bin_dec();
    }
    else if(strcmp(&otsus, "v") == 0){
            break;
    }
    else{
            printf("Sisestasite sobimatu t2he.\n"); //t2he ehk tähe (täpitähti ta ei näita hästi)
    }
    printf("\n");
    }

    system("pause");
    return 0;
}


//Teisendab kahendsüsteemist kümnendsüsteemi
void bin_dec(){
    char jada[20];
    int i;
    int j = 0;
    int arv = 0;
    printf("Sisestage number (1'd ja 0'id): ");
    scanf("%s", &jada);
    printf("\nArv %s on kumnendsusteemis ", jada);
    for(i = strlen(jada); i >= 0; i--){
        arv = arv + atoi(jada[i]) * pow(2, j);
        printf("%d", arv);
        j++;
        }
    }

[DeFiaNT]

atoi doesn't work with char arrays
so do (jada[i]-'0'),this will help

[claudiu]

Well, otsus is supposed to be a string in your logic, but you declare it as one character.

[Subsonics]

Some other things in bin_dec()

- include <string.h> and <stdlib.h>
- initialize i to strlen(jada) -1, or you will be off by one.
- move your printf to outside the loop, unless you want to print the value of arv in each iteration

[P6nn]

Okay!
Now it works fine! Thanks!

[P6nn]

I have now another problem.
I have another program too, but this converts entered integer to binary. Everything works fine, but it prints very strange number to me.
When I ester 2, the answer should be 10, but it gives me lot of strange numbers before it: 557310410 (every time gives different numbers before 10)

#include <stdio.h>
#include <math.h>

void dec_bin();

int main(){
    char otsus = 0;
    while(otsus !=  'v'){
    //Sissejuhatus ja valik
    printf("Mis teisendust on vaja teha:\n");
    printf("b - Kumnendsusteemist kahendsusteemi\n");
    printf("v - V2lju programmist\n");
    printf("Teie otsus: ");
    scanf("%s", &otsus);

    switch(otsus){
       case 'b':
               dec_bin();
               printf("\n");
               break;
       case 'v':
                 break;
      default:
                 printf("\nSisestasite vale t2he\n\n");
                 break;
      }
    }

    system("pause");
    return 0;
}

//Teisendab kümnendsüsteemist kahendsüsteemi
void dec_bin(){
    int str[200];
    int n, x, k;
    int i = 0;
    printf("\nSisestage number:");
    scanf("%d", &n);
    x = n;

    while(n >= 1){
        int number = n%2;
        str[i] = number;
        n = n/2;
        i += 1;
    }
    printf("Arv %d on kahendsusteemis ", x);
    for(k = i ; k >= 0 ; k --){
          printf("%d", str[k]);
          }
    printf("\n");
}

[claudiu]

You are doing the exact same thing. Trying to read a string into a char.