如何从 IP 地址字符串中获取 4 个整数？

Question

I am trying to get 4 integers from an IP-address. For example, 12.34.56.78. A = 12, b = 34, c = 56, and d = 78. Here is my code:

#include <stdio.h>
#include <stdlib.h>
        
int main()
{
    char ADDRESS[100];
        
    printf("Enter IP: ");
    scanf("%s", ADDRESS);
    return 0;
}

How would I be able to do this?

Answer 1

try to use good old sscanf() .

int A, B, C, D;
sscanf(ADDRESS, "%d.%d.%d.%d", &A, &B, &C, &D);

It may be a good idea to check if sscanf() returned 4 what indicates that all four numbers were correctly parsed.

Answer 2

if you're asked to read it as a string at first, you need to add a condition that it exists 4 points in the string

do { 
count=0;
   for (i=0;i<strlen(address);i++) {
        if (address[i] == '.') 
         count++;
         }
 if (count > 4) {
       printf("Enter IP: ");
scanf("%s", ADDRESS); }
while (!(count <= 4));

secondly using strtok can make everything easy, you have to split your string with the . caracter so it goes with something like this

char *tester;
int counter=0,a,b,c,d;
tester = strtok(address, ".");
while( tester != NULL ) {
  switch (counter)  {
   case 0:
   a=atoi(tester);
   counter++;
   break;
   case 1:
   b=atoi(tester);
   counter++;
   break;
   case 2 :
   c=atoi(tester);
   counter++;
   break;
   case 3:
   d=atoi(tester);
   counter++;
   break; }
  tester= strtok(NULL, ".");
}