C Exercises: Convert decimal to binary

Last update on March 20 2025 12:33:33 (UTC/GMT +8 hours)

6. Decimal to Binary Conversion Function Variants

Write a program in C to convert a decimal number to a binary number using the function.

Pictorial Presentation:

Sample Solution:

C Code:

#include<stdio.h>

long toBin(int);

int main()
{
    long bno;
    int dno;
	printf("\n\n Function : convert decimal to binary :\n");
	printf("-------------------------------------------\n");    
    printf(" Input any decimal number : ");
    scanf("%d",&dno);
    bno = toBin(dno);
    printf("\n The Binary value is : %ld\n\n",bno);

    return 0;
}
long toBin(int dno)
{
    long bno=0,remainder,f=1;
    while(dno != 0)
    {
         remainder = dno % 2;
         bno = bno + remainder * f;
         f = f * 10;
         dno = dno / 2;
    }
    return bno;
}

Sample Output:

 Function : convert decimal to binary :
-------------------------------------------
 Input any decimal number : 65

 The Binary value is : 1000001

Explanation:

long toBin(int dno) {
  long bno = 0, remainder, f = 1;
  while (dno != 0) {
    remainder = dno % 2;
    bno = bno + remainder * f;
    f = f * 10;
    dno = dno / 2;
  }
  return bno;
}

The function 'toBin' takes a single argument 'dno' of type int. It converts the input number 'dno' from decimal to binary by repeatedly dividing 'dno' by 2 and storing the remainders in reverse order. The function initializes three local variables, 'bno', 'remainder', and 'f', to 0, 1, and 1 respectively. It then enters a loop that continues as long as 'dno' is not equal to 0. In each iteration of the loop, the remainder of 'dno' divided by 2 is computed and stored in remainder. The value of 'bno' is updated by adding remainder multiplied by 'f'. The value of f is updated by multiplying it with 10. Finally, 'dno' is updated by dividing it by 2. This loop computes the binary equivalent of 'dno' and returns it as a long integer.

Time complexity and space complexity:

The time complexity of this function is O(log n), where n is the input number 'dno', because the loop iterates log_2(n) times to compute the binary equivalent of dno.

The space complexity of this function is O(1), as it only uses a fixed amount of memory to store the three integer variables bno, remainder, and f.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to convert a decimal number to its hexadecimal representation using a function.
Write a C program to convert a decimal number to its octal representation using a dedicated function.
Write a C program to recursively convert a decimal number to binary and print the result from a function.
Write a C program to display the binary representation of a number grouped in 4-bit segments using a conversion function.

C Programming Code Editor:

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