need help checking char strings plz

Hi i just needed a little help in checking strings here is a sample of the code that I need, should be easy to work out what im trying to do.

Code:

---

#include <stdio.h>



int main(void)
{
        char fileName[256];
        FILE *banana;
       
        gets(fileName);

        if (fileName == "banana.dat")
        {
                printf("Yes, fileName is banana.dat, now you can do stuff");
        }
        return 0;
}

---

unfortunatly when i type banana.dat it skips the if statement (so obviously its returning false) would appreciate the help thanx.

Strings cannot be compared with the operator ==. Use:

Code:

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if (strcmp(fileName, "banana.dat") == 0)

---

Instead.

Oh, and don't use gets()

what should I use instead of gets() could you please write the way you would use a better funciton, thanx again

Quote:

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Originally Posted by dezz101

what should I use instead of gets() could you please write the way you would use a better funciton, thanx again

---

fgets() is able to take a maximum length, so that makes it safe. If someone enters a filename longer than 256 in your program bad things will happen.

--
Mats

fgets() is preferrable over gets():

Code:

---

fgets(fileName, 256, stdin);

---

Of course, you may encounter the problem that fgets() leaves a newline character ('\n') on your string. strchr() can help you with that. After the call to fgets(), one may do this:

Code:

---

//Searches for a newline character in fileName
char* location_of_newline = strchr(fileName, '\n');
//If strchr finds it, then it returns a pointer to its location (otherwise it would return NULL). Replace it with a termination character ('\0')
if (location_of_newline != NULL) {
  *location_of_newline = '\0';
}

---

EDIT: Oh, and don't forget to include string.h

thanx hopefully i'll be able to understand that other bit, but I have tried it and it works a treat so thankyou

Umm, why involve the user at all if you just want filename to be "banana.dat"?

Iv realised that what im trying to do wont work, I need the user to enter a file name to open and then open that file for reading. Something like this

dataFile = fopen(("%s", &fileName), "r");

yes I relise this wont work just trying to help you guys understand what I'm trying to do

thats after
insert

Code:

---

{
fgets(fileName, 256, stdin);
//Searches for a newline character in fileName
char* location_of_newline = strchr(fileName, '\n');
//If strchr finds it, then it returns a pointer to its location (otherwise it would return NULL). Replace it with a termination character ('\0')
if (location_of_newline != NULL) {
  *location_of_newline = '\0';
}

---

p.s. how do you wrap code tags in quick reply??

lol found the code tags

I think what you are not understanding is the fact that a user is useless when it comes to making a program function as it is supposed to. More of your program is dedicated to undoing things that the user breaks. GUI's focus on restricting how the user can interfere with what a program is designed to do. Thus, if you are always getting banana.dat, why even ask the user?

To answer your question, however:

Example:

Code:

---

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


int main(void)
{
        char fileName[256];
        FILE *banana;
       
        fgets(fileName, sizeof(fileName), stdin);
        strtok(fileName, "\n");

        if (stricmp(fileName, "banana.dat") == 0) // I am using a non-standard function here... sue me.
        {
                printf("Yes, fileName is banana.dat, now you can do stuff");
        }
        return 0;
}

---

But my program must open any file not just banana.dat, the user should be able to paste a dat file into the program directory and then use the program to perform tasks. sorry for not making that clear

Ok... Well what exactly do you want then? I rewrote your code to do exactly what you asked for it to do in the first place, and now it isn't robust enough for your liking. How about something like this?

Example:

Code:

---

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


int main(void)
{
        char fileName[256];
        FILE *banana;
       
        fgets(fileName, sizeof(fileName), stdin);
        strtok(fileName, "\n");

        if (strstr(fileName, ".dat") != 0)
        {
                printf("Yes, fileName is *.dat, now you can do stuff");
        }
        return 0;
}

---

dont worry I think I got it thanx

Ok..

Perhaps?

Code:

---

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


int main(void)
{
        char fileName[256];
        FILE *banana;
       
        fgets(fileName, sizeof(fileName), stdin);
        strtok(fileName, "\n");

        if (strstr(fileName, ".dat") != 0)
        {
                printf("Yes, fileName is *.dat, now you can do stuff");
                banana = fopen(fileName, "rb");

                if(banana)
                {
                        // do stuff here.

                        fclose(banana);
                }
        }
        return 0;
}

---

I know you said you think you have it, but I figured I'd ask.

lol allready stuck again thanks master was helpful.
I need a function to count the number of rows in a 2 coloumb table and have no idea how I'm going to do it would again, appreciate the help.

i probly should make a new thread for this. so i will

Example:

Code:

---

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

/* This is only a sample to get you started. */
int readDB(FILE *file)
{
  int line = 0;
  char buffer[256];
  int x, y;  // since I don't know the nature of your columns...

  while(!feof(file))
  {
    if(fgets(buffer, 256, file))
    {
        // for good measure, # denote a comment... be creative
        if(*buffer != '#')
            ++line;
        else
        {
            sscanf(buffer, "&#37;d %d", &x, &y);
            printf("%04d (%d, %d), line, x, y);
        }
    }
  }

  return line;
}

int main(void)
{
        char fileName[256];
        FILE *banana;
       
        fgets(fileName, sizeof(fileName), stdin);
        strtok(fileName, "\n");

        if (strstr(fileName, ".dat") != 0)
        {
                printf("Yes, fileName is *.dat, now you can do stuff");
                banana = fopen(fileName, "rb");

                if(banana)
                {
                        // do stuff here.
                        readDB(banana);

                        fclose(banana);
                }
        }
        return 0;
}

---

Code:

---

while(!feof(file))
  {
    if(fgets(buffer, 256, file))

---

better looks:

Code:

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while(fgets(buffer, sizeof buffer, file))

---

otherwise - if fgets failed due to some error that does not signals eof condition - you'll get the infinite loop