POJ2105:IP Address

Description

Suppose you are reading byte streams from any device, representing IP addresses. Your task is to convert a 32 characters long sequence of '1s' and '0s' (bits) to a dotted decimal format. A dotted decimal format for an IP address is form by grouping 8 bits at a time and converting the binary representation to decimal representation. Any 8 bits is a valid part of an IP address. To convert binary numbers to decimal numbers remember that both are positional numerical systems, where the first 8 positions of the binary systems are:

27   26  25  24  23   22  21  20 128 64  32  16  8   4   2   1 

Input

The input will have a number N (1<=N<=9) in its first line representing the number of streams to convert. N lines will follow.

Output

The output must have N lines with a doted decimal IP address. A dotted decimal IP address is formed by grouping 8 bit at the time and converting the binary representation to decimal representation.

Sample Input

400000000000000000000000000000000 00000011100000001111111111111111 11001011100001001110010110000000 01010000000100000000000000000001 

Sample Output

0.0.0.03.128.255.255203.132.229.12880.16.0.1

我擦，用int数组的话居然一直没弄出答案，改用char很快就正确了，什么原因？

#include <stdio.h>#include <iostream>#include <math.h>using namespace std;int main(){    int n;    char a[35];    cin >> n;    getchar();    while(n--)    {        int i;        gets(a);        for(i = 0; i<32; i++)        {            if((i+1)%8 == 0)            {                int j,sum = 0;                for(j = i-7; i-j>=0; j++)                {                    if(a[j]!='0')                        sum = sum+pow(2.0,(i-j));                }                cout << sum;                if(i!=31)                    cout << ".";            }        }        cout << endl;    }    return 0;}