In this C program, we will learn about how to find two complement of a binary number.

#### Required Knowledge

**Algorithm to find twos complement of a binary number**

- To find the
**twos complement**of a number first find the ones complement by toggling the bits of the number. Change all 1's to 0's and all 0's to 1's. - Add binary 1 to the ones complement to get
**twos complement**.

For Example :

**Binary Number** = 00101011

**Ones Complement** = 11010100

**Twos Complement** = 11010101

## C program to find two complement of a binary number

#include <stdio.h> #include <string.h> int main() { char binaryNumber[100], onesComplement[100], twosComplement[100]; int counter, error=0, digitCount, carry = 1; printf("Enter a Binary Number\n"); scanf("%s", binaryNumber); digitCount = strlen(binaryNumber); for(counter=0; counter < digitCount; counter++) { if(binaryNumber[counter]=='1') { onesComplement[counter] = '0'; } else if(binaryNumber[counter]=='0') { onesComplement[counter] = '1'; } else { printf("Error :( "); return 1; } } onesComplement[digitCount] = '\0'; for(counter = digitCount-1; counter >= 0; counter--) { if(onesComplement[counter]=='1' && carry==1){ twosComplement[counter] = '0'; } else if(onesComplement[counter]=='0' && carry==1) { twosComplement[counter] = '1'; carry = 0; } else { twosComplement[counter] = onesComplement[counter]; } } twosComplement[digitCount] = '\0'; printf("Two's Complement : %s", twosComplement); return 0; }Output

Enter a Binary Number 11100001 Two's Complement : 00011111

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