CareerCup-5.2

Given a (decimal - e g 3.72) number that is passed in as a string, print the binary representation. If the number can not be represented accurately in binary, print “ERROR”.

答案没有考虑负数的情况。但是有没有负数从题目无法推断出。

#include <iostream>
#include <bitset>
using namespace std;
typedef int Data;

void printDecimal(string s)
{
    int size = s.size();
    if(size<1)
    {
        cout<<"Error"<<endl;
        return;
    }
    string r;
    int i=0;
    if(s[i] == '+' || s[i] == '-')
    {
        r += s[i++];
        if(size == 1)
        {
            cout<<"Error"<<endl;
            return;
        }
    } else {
        r += '+';
    }
    int index = s.find(".", i);
    if(index < 1)
    {
        cout<<"Error"<<endl;
        return;
    }
    string s1 = s.substr(0, index);
    string s2 = s.substr(index+1, size);
    if(s1.size() < 1 || s2.size() < 1)
    {
        cout<<"Error"<<endl;
        return;
    }
    int d1 = atoi(s1.c_str());
    int d2 = atoi(s2.c_str());
    int len = 1;
    for(int j=s2.size()-1; j>=0; j--)
    {
        len *= 10;
    }
    do
    {
        r += '0' + d1%2;
        d1 = d1/2;
    } while(d1 != 0);
    reverse(r.begin()+1, r.end());
    r += '.';
    int count = 32;
    do
    {
        d2 *= 2;
        r += d2>=len?'1':'0';
        d2 = d2%len;
        count--;
    } while(d2 != 0 && count > 0);
    if(count == 0)
        r = "ERROR";
    cout<<r<<endl;
};

int main()
{
    string s = "3.375";
    printDecimal(s);
    system("pause");
};