Search using strncmp and strlen?

[philia]

So, my program has a search option to search from a file. But here, I'm using strcmp function so the strings has to match exactly with the compared string.
My instructor told me to use strncmp and strlen to make the search option better. Although I don't know how to use it.
Here is the code:

int search()
{
     char target[50];
     int flag=0;



     struct item food;

      FILE *pfile;

    pfile = fopen("food menu.txt","rb");

   if(pfile != NULL)
   {
       printf("Enter Item name\n");
       scanf("%s",&target);
       fflush(stdin);

        do
         {
             fread(&food,sizeof(food),1,pfile);

             if(!feof(pfile));
             {
    if(strcmp(target,food.item_name)==0)
    {

         printf("\n%-20s %18s %28.2f\n",food.item_name,food.item_type,food.item_price);
         flag=1;
         system("pause");
         return SUCCESS;

    }
             }

    }while(!feof(pfile));
    }fclose(pfile);

  if(flag==0)
     {
         printf("NO MATCH FOUND");
     }


}

Any help would be appreciated. Thanks.

[laserlight]

Why not use strstr? In fact, I think that this has been suggested to you in a previous thread (if I did not mistake you for another member).

[philia]

^I didn't posted any thread like this. So this must be a misunderstanding. But I'll look up strstr. I've never heard of it though.

[laserlight]

Ah, my apologies for the mistaken identity.

By the way, to read a string into an array named target with scanf, you would pass target, not &target, as the argument. Also, to avoid buffer overflow, you would use "%49s", not just "%s", since the string can have a length of at most 49 (remember there must be space for the null character).

Oh, and note that fflush(stdin) results in undefined behaviour.

[philia]

Ah...I see. Thanks. My program is working though, but I'll apply these changes.

But my real question is how do I use strstr, strncmp or ctelen in that function.

[laserlight]

But my real question is how do I use strstr, strncmp or ctelen in that function.

You need to read up on the relevant documentation first, e.g., if you are on a *nix system, [b]man strstr[/man] will show you what are the parameters and return type of strstr and what does it do, and from there you can decide how you might use it: though you need to be clear on what you are trying to do. You could also search the Web.

[TAZIN]

strlen function basically computes the of a string, and in your case you'd use this function on the word that the user is looking for....(i.e. int iLen = strlen(target); ). The strncmp function is almost the same as the strcmp function your already using except it has an additional parameter; int size. So, basically you'd use the resultant from the strlen() function (int iLen) as the additional parameter (int size) in the strncmp() function. i.e. strncmp (target, food.item_name, iLen).

[Salem]

Another poster that could do well to learn the benefit of indentation.

int search()
{
  char target[50];
  int flag = 0;

  struct item food;

  FILE *pfile;
  pfile = fopen("food menu.txt", "rb");

  if (pfile != NULL) {
    printf("Enter Item name\n");
    scanf("%s", &target);
    fflush(stdin);

    do {
      fread(&food, sizeof(food), 1, pfile);

      if (!feof(pfile));
      {
        if (strcmp(target, food.item_name) == 0) {

          printf("\n%-20s %18s %28.2f\n", food.item_name, food.item_type,
                 food.item_price);
          flag = 1;
          system("pause");
          return SUCCESS;
        }
      }
    } while (!feof(pfile));
  }
  fclose(pfile);

  if (flag == 0) {
    printf("NO MATCH FOUND");
  }
}

A couple of points
1. if (!feof(pfile)); does nothing, because of the ; at the end.
2. You return SUCCESS without ever closing the file.

[vart]

I would test return value of fread instead of feof flag for indication of the read success.

while(1 == fread(&food, sizeof(food), 1, pfile))
{
        if (strcmp(target, food.item_name) == 0) {
 
          /* do your stuff */
        }
}

PS. fflush(stdin) is undefined. This function is used for outgoing streams to force the current content of the stream buffer to appear on the screen or be written into the file. (without waiting for end-of line to appear in the stream for line buffered streams, for example)