IP判断 （C语言代码）

#include <stdio.h>
#include <string.h>
int main()
{
     int i=0,j,flag=1,s=0;
     char a[1000][31];

     while(scanf("%s",&a[i])!=EOF)
     {
              flag=1;s=0;
              for(j=0;a[i][j]!='\0';j++)
              {
                  if((a[i][0]=='0')&&('0'<=a[i][j]&&a[i][j]<='9')){flag=0;break;}
                  if(a[i][j]=='.'&&a[i][j]=='0'&&('0'<=a[i][j]&&a[i][j]<='9')){flag=0;break;}
                  if(!(('0'<=a[i][j]&&a[i][j]<='9')||(a[i][j]=='.'))){flag=0;break;}     
                  if('0'<=a[i][j]&&a[i][j]<='9')
                  {
                        s=s*10+(a[i][j]-48);
                        if(a[i][j+1]=='.')
                        {
                              if(0<=s&&s<=255){flag=1;s=0;}
                              else{flag=0;s=0;break;}
                         }
                   }     
               }
               if(flag==0)printf("N\n");
               else printf("Y\n");
               i++;
       };

       return 0;
}

解题思路:





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参考代码: