/prog/ - What gives?

Name: Anonymous 2010-01-17 10:09

I have a text file called bigint that reads:



3

1 8888888888 2222222222

2 9999999999 10000000000

2 10000000000 9999999999

Yet everytime I run the following code:



#include <stdio.h>

#include <string.h>



int main(){

    

    FILE *ifp;

    char* LOLSTRING;

    int lawl, lawl2;

    

    ifp = fopen("bigint.txt", "r");

    

    fscanf(ifp, "%d", &lawl);

    fscanf(ifp, "%d", &lawl2);

    fscanf(ifp, "%s", LOLSTRING);

    

    printf("%s\n", LOLSTRING);

    

    fclose(ifp);



    system("pause");



    return 0;

}

... the program crashes AFTER the pause is run. Meaning, whenever I press any key, it somehow shits itself. What gives?

Name: Anonymous 2010-01-17 10:19

I know it has something to do with assigning memory to the character array, but why does it fuck up only after it does its part?

Name: Anonymous 2010-01-17 10:20

>>1
I see a couple of problems:
char* LOLSTRING;
You need to alloc that string somewhere, otherwise fscanf will write to random memory. fscanf itself isn't even safe, as you could read in a string bigger than your alloced memory, thus making your program suspectible to a heap or stack overflow(depending on how you alloc it)
system("pause");
Is this necesarry? Run your application from a command line interface, terminal or whatever.
ifp = fopen("bigint.txt", "r");
You're not checking the return value here, file bigint.txt may not exist or it may already be open or something of that sort.

Name: Anonymous 2010-01-17 10:24

I run it from DevC++, writing system("pause"); or getchar() is just the way I've been taught.

Also, this isn't a real program or assignment, just something I cooked up to test something I noticed while doing something else, so I already know the file is there and functional.

Name: Anonymous 2010-01-17 10:31

This all sucks but the easiest way to fix it is probably changing char* LOLSTRING; to char LOLSTRING[9001]; and then passing it as &LOLSTRING (or maybe arrays *ARE* pointers, I don't remember. Just try with and without &)

Name: Anonymous 2010-01-17 12:27

>>2-5
IT'S LIKE I'M REALLY ON REDDIT

Name: Anonymous 2010-01-17 12:53

or maybe arrays *ARE* pointers, I don't remember
Have you read your K&R today?

Name: Anonymous 2010-01-17 16:29

Only elite programmers can ask programming-related questions. Except they don't, because they already know where to look to find their answers.

Sage.

Name: Anonymous 2010-01-17 20:50

system("pause");
GET THE FUCK OUT

Name: Anonymous 2010-01-17 22:30

>>9
Yawn.

Name: Anonymous 2010-01-17 23:49

>>2-5
I despair'd.

Name: Anonymous 2010-01-18 0:33

pausing

You wouldn't have this problem if you compiled and executed your programs from a command line. Why don't you take your kiddie IDE toys out of /prog/ and leave the adults to their work?

Name: Anonymous 2010-01-18 1:48

>>12
0/10. If your post had any merit, you wouldn't have the time to post.

Name: Anonymous 2010-12-22 1:40

Don't change these.

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Entire Thread Thread List

What gives?

1 Name: Anonymous 2010-01-17 10:09

2 Name: Anonymous 2010-01-17 10:19

3 Name: Anonymous 2010-01-17 10:20

4 Name: Anonymous 2010-01-17 10:24

5 Name: Anonymous 2010-01-17 10:31

6 Name: Anonymous 2010-01-17 12:27

7 Name: Anonymous 2010-01-17 12:53

8 Name: Anonymous 2010-01-17 16:29

9 Name: Anonymous 2010-01-17 20:50

10 Name: Anonymous 2010-01-17 22:30

11 Name: Anonymous 2010-01-17 23:49

12 Name: Anonymous 2010-01-18 0:33

13 Name: Anonymous 2010-01-18 1:48

15 Name: Anonymous 2010-12-22 1:40