Decimal to Binary in C

To convert a decimal number to binary in C, you can use a loop that repeatedly divides the decimal number by 2 and keeps track of the remainders. The remainders, read in reverse order, form the binary representation of the decimal number. Here’s a C program to perform this conversion:

#include <stdio.h>

int main() {
    int decimalNum;
    printf("Enter a decimal number: ");
    scanf("%d", &decimalNum);

    if (decimalNum < 0) {
        printf("Negative numbers are not supported for this example.\n");
        return 1;
    }

    int binary[32]; // Array to store binary digits (32 bits for an int)
    int index = 0;

    while (decimalNum > 0) {
        binary[index] = decimalNum % 2;
        decimalNum /= 2;
        index++;
    }

    if (index == 0) {
        // The input was 0
        printf("Binary: 0\n");
    } else {
        printf("Binary: ");
        for (int i = index - 1; i >= 0; i--) {
            printf("%d", binary[i]);
        }
        printf("\n");
    }

    return 0;
}

In this program:

• We take a decimal number as input from the user.
• We check if the input number is negative, and if it is, we print an error message and exit the program.
• We use an array binary to store the binary digits of the number. We assume a maximum of 32 bits for an integer, so the array size is set to 32.
• We use a while loop to repeatedly divide the decimal number by 2 and store the remainder (0 or 1) in the binary array. This process continues until the decimal number becomes 0.
• Finally, we print the binary representation by iterating through the binary array in reverse order.

Compile and run the program, and it will convert the entered decimal number into its binary representation.