WAP to convert binary to decimal number using user define function.
Objective
Write a C++ program to convert a Binary number to Decimal using a function.
Algorithm / Approach
- Write a custom
power()function. - In
binToDec(), extract each digit (rem = n % 10). - Multiply the digit by 2 raised to the power of its position index.
- Add it to the decimal total.
main.cpp
#include<iostream>
#include<math.h>
using namespace std;
long binToDec(long n);
int power(int, int);
int main() {
long bi;
cout<<"Enter a binary no. :";
cin>>bi;
cout<<"BINARY : "<< bi<< endl;
cout<<"DECIMAL: "<< binToDec(bi);
return 0;
}
long binToDec(long n) {
int rem;
long dec = 0, i=0;
while(n != 0) {
rem = n%10;
n = n/10;
dec = dec +(rem*power(2,i));
++i;
}
return dec;
}
int power(int a, int b) {
int res= 1;
for(int i =0; i< b; i++) {
res = res*b;
}
return res;
}Expected Output
Enter a binary no. :11011 BINARY : 11001 DECIMAL : 27
Explanation of the Program
- Binary to decimal conversion involves multiplying each binary digit by 2^position and summing the results.
- Note on the provided code: There is a severe logical bug in the custom
power(int a, int b)function. Inside the loop, it calculatesres = res * b;. This calculates (B to the power of B), entirely ignoring the basea! It should beres = res * a;.
Complexity
Time Complexity
O(log₁₀ n) - For extracting digits.
Space Complexity
O(1)
Common Mistakes
- Logical Error: The custom power function multiplies the exponent by itself (
res = res * b) instead of the base (res = res * a).
