北大暑假训练计划—POJ2105 IP Address（C语言）

                                                                                                                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

4
00000000000000000000000000000000
00000011100000001111111111111111
11001011100001001110010110000000
01010000000100000000000000000001
Sample Output

0.0.0.0
3.128.255.255
203.132.229.128
80.16.0.1

 

#include<stdio.h>
#include<string.h>
int main()
{
    int i,a,b,c,d,n;
 char s[40];
    scanf("%d",&n);
 getchar();
    while(n--)
    {
 gets(s);//输入后面可以有空格，所以数组开的比32大一点才可以，而且要用ges()输入，才可以输入空格
    a=0;
    b=0;
    c=0;
    d=0;
    for(i=0;i<32;i++)
    {
    if(i/8==0)
    {
    a=a*2+(s[i]-'0');
    }
    else if(i/8==1)
    {
    b=b*2+(s[i]-'0');
    }
    else if(i/8==2)
    {
    c=c*2+(s[i]-'0');
    }
    else if(i/8==3)
    {
    d=d*2+(s[i]-'0');
    }
   }
   printf("%d.%d.%d.%d\n",a,b,c,d);
   }
   return 0;
}