Decimal to Binary convert in C

Question

My simple program fails to convert 7 to 111 (the current code gives 101). I know myArray[] and the last printf() can be improved, but we can talk about that next time.

int main() {
    int myDecimal, quo, rem;
    int i = 0; //counter
    int myArray[3];
    printf("Enter valid decimal number: ");
    scanf("%d", &myDecimal);

    while(quo != 1){
        quo = myDecimal / 2;
        rem =  myDecimal % 2;

        myArray[i] = rem;
        myDecimal = quo;
        i++;
    } myArray[i] = quo;

    printf("\nBinary: %d %d %d", myArray[i + 2], myArray[i + 1], myArray[i] );  
    return 0;
}

Answer 1

It's work fine for me. have you include header files properly? and which compiler do you using ?

#include <stdio.h>
#include <conio.h>

int main() {
    int myDecimal, quo, rem;
    int i = 0; //counter
    int myArray[3];
    printf("Enter valid decimal number: ");
    scanf("%d", &myDecimal);

    while(quo != 1){
        quo = myDecimal / 2;
        rem =  myDecimal % 2;

        myArray[i] = rem;
        myDecimal = quo;
        i++;
    } myArray[i] = quo;

    printf("\nBinary: %d %d %d", myArray[i + 2], myArray[i + 1], myArray[i] );
    return 0;
}

Output

I also try this. you also can try this if you want :)

#include <stdio.h>
#include <conio.h>

int main() {
    long myDecimal;
    long binary = 0, i = 1;
    int rem;
    printf("Enter valid decimal number: ");
    scanf("%d", &myDecimal);

    while(myDecimal != 0) {
        rem = myDecimal%2;
        myDecimal = myDecimal/2;
        binary= binary + (rem*i);
        i = i*10;
    }
    printf("Binary number is %ld",binary);
}

Answer 2

There's some errors that should be taken care of..

1. Initialize the array because for conversion of 1, it maybe garbage 0 1
2. Don't force the myArray[i] = quo;
3. You should take care of printing as i maybe of different length and may cause unstable behavior.
4. Also initialize quo before use as it may lead to garbage comparison.

5. Also follow the tips in comments, they are useful.

   int main() {
   int myDecimal, quo, rem;
   int i = 0; //counter
   int myArray[3] = {0};
   printf("Enter valid decimal number: \n");
   scanf("%d", &myDecimal);
   quo = myDecimal;
   while(quo > 0){
       quo = myDecimal / 2;
       rem =  myDecimal % 2;
   
       myArray[i] = rem;
       myDecimal = quo;
       i++;
   } 
   printf("Binary: %d %d %d", myArray[2], myArray[1], myArray[0]);  
   return 0;
   }
   

Answer 3

By your logic you have used you need to make smaller changes to get this to work.

check.c

#include<stdio.h>

int main() {
int myDecimal, quo, rem;
int i = 0; //counter
int myArray[3];
printf("Enter valid decimal number: ");
scanf("%d", &myDecimal);
//check myDecimal whether it's above 0 after each iteration
while(myDecimal > 0){
    quo = myDecimal / 2;
    rem =  myDecimal % 2;

    myArray[i] = rem;
    myDecimal = quo; 
    i++;
} myArray[i] = quo;
//print the array in the reverse order
for(i=2;i>=0;i--){
printf("%d",myArray[i]);
}  
printf("\n");
return 0;
}

Ouput: