Thread: Weird bug in string array output

So here's the code

Code:

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


void main(int argc, char **argv)
{
  int i,x,size,wordnum,friends;
  char max[256],buffer[256];
  char *fname,*prev,*curr;
  FILE *file;
  friend *friendArray;


  //Check for command line arguments
  if (argc <= 1)
    {
      printf("Insufficient number of inputs\n");
      exit(1);
    }


  //Open the file and check if file exists
  fname = argv[1];
  file = fopen(fname,"r");


  if (file == NULL)
    {
      printf("Cannot open input file %s\n",fname);
      exit(2);
    }


  //Read in file line by line and search word
  while(!feof(file))
    {
      fgets(max, sizeof(max), file);


      prev = strtok(max," ");
      while((curr = strtok(NULL," ")) != NULL)
    {
      if (strstr(curr, "circle") != NULL)
        {
          printf("%s %s",prev,curr);
          //Skip lines amounting to number of circles
          for(i=1;i<=atoi(prev);i++)
        printf("\n");
        }
      if (strstr(curr, "friend") != NULL)
        {
          //Allocate array with the number of friends
          friendArray = (friend *)malloc(sizeof(friend)*atoi(prev)+1);
             friends = atoi(prev);
             printf("%s %s",prev,curr);


          //Insert items into array using for loop
          for(x=0;x<friends;x++)
        {
                  fgets(buffer,256,file);
            friendArray[x].firstname = strtok(buffer," ");
            friendArray[x].lastname = strtok(NULL," ");
            strcpy(friendArray[x].birthdate,strtok(NULL," "));
        }
             defaultPrint(friendArray,friends,stdout);
        }      
    }
    } 
  fclose(file);
}

Here's the struct

Code:

#include <stdio.h>
#include <stdlib.h>
#include "printFriends.h"


void defaultPrint(friend *array, int num_friends, FILE *outfile)
{
	int i;
	printf("Default print function\n");
	for(i=0;i<num_friends;i++)
		fprintf(stdout,"%d: %s, %s, %s\n",i,
			array[i].lastname,
			array[i].firstname,
			array[i].birthdate);
	
}

The output I get is
0: ri, Kasturi, 03031983
1: ri, Kasturi, 07011975
2: , Kasturi, 08251983
3: ri, Kasturi, 01012001
4: Hansen, Kasturi, 10051950

The output I want is
Zhang, Jane 03031983
Hernandez, John 07011975
Smith, Wenyue 08251983
Wassal, Jose 01012001
Hansen, Kasturi 10051950

My code just seems to take the last name on the list which is weird and I don't understand why.

You aren't actually copying any memory (the names) anywhere. You are just making (unknown pointers, since you didn't show us the definition of your structure) pointers point at the buffer that strtok returns. This would normally give you an error of sorts, since the function isn't creating any dynamic memory, and a normal array would have gone out of scope. Since strtok actually uses a static buffer, you get whatever is in there currently. All your name pointers end up pointing to the same space.


Quzah.

Switch from pointers to arrays in your structure, or dynamically allocate memory, and copy the data strtok has saved before you call it again.


Quzah.