Split string with multiple delimiters using strtok in C

Question

I have problem with splitting a string. The code below works, but only if between strings are ' ' (spaces). But I need to split strings even if there is any whitespace char. Is strtok() even necessary?

char input[1024];
char *string[3];           
int i=0;

fgets(input,1024,stdin)!='\0')               //get input
{                                        
  string[0]=strtok(input," ");               //parce first string
  while(string[i]!=NULL)                     //parce others
  {
     printf("string [%d]=%s\n",i,string[i]);
     i++;
     string[i]=strtok(NULL," ");
  }

Answer 1

A simple example that shows how to use multiple delimiters and potential improvements in your code. See embedded comments for explanation.

Be warned about the general shortcomings of strtok() (from manual):

These functions modify their first argument.

These functions cannot be used on constant strings.

The identity of the delimiting byte is lost.

The strtok() function uses a static buffer while parsing, so it's not thread safe. Use strtok_r() if this matters to you.

---

#include <stdio.h>
#include<string.h>

int main(void)
{    
  char input[1024];
  char *string[256];            // 1) 3 is dangerously small,256 can hold a while;-) 
                                // You may want to dynamically allocate the pointers
                                // in a general, robust case. 
  char delimit[]=" \t\r\n\v\f"; // 2) POSIX whitespace characters
  int i = 0, j = 0;

  if(fgets(input, sizeof input, stdin)) // 3) fgets() returns NULL on error.
                                        // 4) Better practice to use sizeof 
                                        //    input rather hard-coding size 
  {                                        
    string[i]=strtok(input,delimit);    // 5) Make use of i to be explicit 
    while(string[i]!=NULL)                    
    {
      printf("string [%d]=%s\n",i,string[i]);
      i++;
      string[i]=strtok(NULL,delimit);
    }

    for (j=0;j<i;j++)
    printf("%s", string[i]);
  }

  return 0;
}