C Program to convert binary number into its equivalent Decimal, Octal, and Hexadecimal representations. In this program we convert a binary number to decimal. Then convert that decimal number to octal and Hexadecimal equivalent.

The program implements various functions to do the job.

- binary_to_decimal : Convert given binary number to it’s decimal equivalent
- decimal_to_octal : Convert from decimal to octal
- decimal_to_hex : Convert from decimal to hexadecimal

The main function takes care of getting input from user, calling the above functions and displaying the results.

Read more here: What are binary, octal, and hexadecimal notation?

Contents

### The Program

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#include <stdio.h> | |

/* | |

* Function to convert a given decimal number to its | |

* hexadecimal equivalent. | |

*/ | |

int decimal_to_hex(long number, char *hexstr, int pos) { | |

long i; | |

int new_position, n; | |

char hexchar; | |

new_position = pos; | |

if(number > 0) { | |

i = number % 16; | |

n = number / 16; | |

new_position = decimal_to_hex(n, hexstr, pos); | |

if(i >= 10) { | |

switch(i) { | |

case 10: hexchar = 'A'; break; | |

case 11: hexchar = 'B'; break; | |

case 12: hexchar = 'C'; break; | |

case 13: hexchar = 'D'; break; | |

case 14: hexchar = 'E'; break; | |

case 15: hexchar = 'F'; break; | |

} | |

} else { | |

hexchar = '0' + i; | |

} | |

hexstr[new_position++] = hexchar; | |

hexstr[new_position] = '\0'; | |

} | |

return new_position; | |

} | |

/* | |

* Function to convert a given binary number to | |

* its decimal equivalent. | |

*/ | |

int binary_to_decimal(int num) { | |

int rem, base = 1, decimal_number = 0; | |

while( num > 0) { | |

rem = num % 10; | |

if((rem == 0) || (rem == 1)) { | |

decimal_number = decimal_number + rem * base; | |

num = num / 10 ; | |

base = base * 2; | |

} else { | |

return -1; // Invalid binary number | |

} | |

} | |

return decimal_number; | |

} | |

/* | |

* Function to convert a given decimal number in to | |

* its octal equivalent. | |

*/ | |

int decimal_to_octal(int number) { | |

int octal_number = 0, rem, base = 1; | |

while(number > 0) { | |

rem = number % 8; | |

octal_number = octal_number + rem * base; | |

base = base * 10; | |

number = number / 8; | |

} | |

return octal_number; | |

} | |

void main() { | |

int binary_numer, decimal_number, octal_number; | |

char hexstr[25] = "0"; | |

printf("Enter a binary number: "); | |

scanf("%d", &binary_numer); | |

printf("Given Binary number is: %d\n", binary_numer); | |

decimal_number = binary_to_decimal(binary_numer); | |

if(decimal_number == -1) { | |

printf("\nInvalid binary number. Try again."); | |

return; | |

} | |

printf("Its Decimal equivalent is: %d", decimal_number); | |

octal_number = decimal_to_octal(decimal_number); | |

printf("\nIts octal equivalent is: %d", octal_number); | |

decimal_to_hex(decimal_number, hexstr, 0); | |

printf("\nIts Hexa Decimal equivalent is: %s", hexstr); | |

} |

### Sample Output

### Related Programs

- C Program to convert Binary number to Decimal
- C program to find the 2’s complement of a binary number
- C Program to convert a given decimal number into its binary equivalent

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### Edit1 : 11th August 2017

- Added screenshot of sample runs
- Moved the code to it’s own Gist
- Modified the program to make it more modular

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## 3 comments on “C program to convert a Binary number into its equivalent Decimal, Octal and Hexadecimal numbers.”

C program to convert a binary number to decimal,octal and hexadecimal number and back

what about fractional number…do you have any idea?…please share.