How to fetch a specific substring from string and separately print it?

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C

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

int main(){
  char str[] = "bilal,1000,savings";
  char toFind; 
  char * word1;
  char * word2;
  char * word3;
  int i=0, numberOfFields = 3;
  static const char * listing[] = {"Name","Amount","Account"};
  char name[20], account[20];
  int amount;

  for(i=0; i<numberOfFields; i++){
    printf("%d. Here is your %s \n", i, listing[i]);
  }

  printf("Which one: ");
  scanf("%c", &toFind);

  if(toFind == '0'){
    printf("selected zero\n");
    word1 = strtok(str, ",");
    printf("%s\n", word1);
  }

  else if(toFind == '1'){
    printf("selected one\n");
  }

  else if(toFind == '2'){
    printf("selected two\n");
  }
  return 0;
}

What I have tried:

In this code, I want to select the second word from the file and the third one also and print that one but I am unable to fetch specific words. I searched a lot and done a lot of stuff to fetch the second and third words from the str variable but unable to do that?

Posted 31-Aug-20 9:38am

ibilalkayy

Updated 31-Aug-20 20:11pm

CPallini

v3

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k5054 · Accepted Answer · 2020-08-31T12:26:00

After the initial call to strtok() you can pass NULL as the first parameter and strtok will use the previously supplied string buffer to return the next string.

word1 = strtok(str, ",");
word2 = strtok(NULL, ",");
word3 = strtok(NULL, ",");
if( toFind == '0') {
    printf("%s\n", word1);
}

or perhaps, more usually:

C

char *words[3];
i = 0;
for(word = strtok(str, ","); word != NULL; word = strtok(NULL, ",") {
    words[i++] = word;
}

int whichWord = atoi(toFind);
/* should check whichWord is in bounds here ... */

whichWord -= 1; /* user will have entered 1-3, but array runs 0-2 */
printf("%s\n", words[whichWord];

Note that if we need to increase the number of fields, all we need to do is to change char *words[3] to maybe char *words[10]. We could even dynamically allocate the variable words by counting the commas in the input string and then use a call to malloc() to create the needed space.

Be aware that strtok() modifies the input buffer, so you must not use a const char, as this will almost certainly cause a runtime error. Also, since the input buffer is modified, if you need to re-parse the input buffer, in this case, it will have all commas replaced with nul chars ('\0'). In that case, you might want to make a copy of the original input buffer, perhaps using strdup()