Part 2 of binary conversion assignment

BinaryToFloat.cpp

#include <stdio.h>
#include <iostream>
#include <string>
#include <cmath>

using namespace std;


int main(){
	cout << "Enter binary: ";
	
	string binary;
	binary = "";
	getline(cin,binary);

	double exponent = 0;
	double mantissa = 0;
	int sign = 1;

	if (binary == "11111111111111111111111111111111"){
		cout << "NaN";
	} else if (binary == "00000000000000000000000000000000"){
		cout << "0";
	} else if (binary == "10000000000000000000000000000000"){
		cout << "-0";
	} else if (binary == "01111111100000000000000000000000"){
		cout << "infinity";
	} else if (binary == "11111111100000000000000000000000"){
		cout << "-infinity";
	} else {
		for (int i = 0; i < binary.length(); i++){
			if (i == 0){					// sign
				if (binary[i] - '0' == 1) sign = -1;
			} else if (i > 0 && i < 9){		// exponent
				exponent += (binary[i] - '0') * pow(2, (8 - i));
			} else {						// mantissa
				mantissa += (binary[i] - '0') * pow(2, ((binary.length() - 1) - i));
			}
		}

		exponent -= 127;
		mantissa /= pow(2, 23);

		cout << "decimal: " << sign * (1 + mantissa) * pow(2, exponent) << "\n";
	}
	
	getchar();
}