2’s complement of a number is obtained by scanning it from right to left and complementing all the bits after the first appearance of a 1. Thus 2’s complement of 11100 is 00100. Write a C program to find the 2’s complement of a binary number.
Algorithm:
Step 1: Start Step 2: declare the subprogram “complement(char *a)” Step 3: initialize the variable i Step 4: read the binary number Step 5: perform the loop operation. if it is true then follows. if not goto step 7 i) for(i = 0; a[i]! = ’\0’; i ) ii) if(a[i] != ’0’ && a[i]! = ’1’) then displayed the number is not valid. enter the correct number. iii) Exit the loop Step 6: call sub program ‘complemt(a)’ Step 7: Stop
Sub Program:
Step 1: initialize the variable I, c = 0, b[160] Step 2: 1 = strlen(a) Step 3: perform the loop operation. if it is true then follows. if not goto i) for(i = l  1; i >= 0; i) ii) if(a[i] == ’0’) then b[i] = ’1’ else iii)b[i] = ’0’ Step 4: for(i = l  1; i >= 0; i) is true i) if(i == l  1) then ii) if(b[i] == ’0’) then b[i] = ’1’ else iii)b[i] = ’0’, c = 1 if not goto step 5 Step 5: if(c == 1 && b[i] == ’0’) is true then i)b[i] = ’1’, c=0 if not goto Step 6 Step 6: if(c == 1 && b[i] == ’1’) then b[i] = ’0’, c = 1 Step 7: displayed b[l] = ’\0’ Step 8: print b and return to main program
Program:
#include <stdio.h> #include <string.h> #include <conio.h> void main() { char a[20]; int i, carry, l; clrscr(); printf("Enter the binary number \n"); scanf("%s", &a); l = strlen(a); for(i = 0; i < l; i++) { if(a[i] == '0') { a[i] = '1'; } else { a[i] = '0'; } } printf("The 1's compliment of the binary number is %s \n", a); i = strlen(a)  1; while(i >= 0) { if(a[i] == '0') { a[i] = '1'; carry = 0; break; } else { a[i] = '0'; carry = 1; i = i  1; } } printf("The 2's compliment of the binary number is "); if(carry == 1) { printf("1"); } printf("%s", a); getch(); }
Input & Output:
Enter the binary number 100101 The 1’s compliment of binary number is 011010 The 2’s compliment of binary number is 011011

CreatedOct 11, 2014

UpdatedDec 25, 2014

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