IP判断 （C语言代码）

解题思路:





注意事项:





参考代码:

#include <stdio.h>

#include <string.h>

#include <math.h>

int main(void)

{

int i, k, flag, digit, length, count;

char ch[31];

while (gets(ch) != NULL && strcmp(ch, "End of file"))

{

k = 0;

count = 0;

length = strlen(ch);

while (count <= 3)

{

digit = 0;

if(ch[k]=='0')

{

digit = -1;

flag = 0;

break;

}

else

flag = 1;

while (ch[k] != '.' && k < length)

k++;

for (i = k - 1;i >= 0;i--)

{

if (ch[i] == '.')

break;

else if (ch[i] > '9' || ch[i] < '0')

{

digit = -1;

flag = 0;

break;

}

else

digit = digit + (ch[i] - '0')*pow(10, k - i - 1);

}

if (digit > 255 || digit < 0)

{

flag = 0;

break;

}

else

{

flag = 1;

count++;

}

if (flag == 0)

break;

else

k++;

}

if (flag == 1)

printf("Y\n");

else

printf("N\n");

}

return 0;

}