Thread: Reading from an data?

You're trying to read a double with %s.


Quzah.

You were close, the changes I made are in red and read the comments I added.

Code:

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

int main(int argc, char *argv[])
{
    FILE *fin, *fout;
    char text[81], text2[81], first[40], last[40], sale[40], car[40];
    int lines;
    int number;    //no one ever has 4.3798 cars, this only needs to be an integer.

    fin = fopen("/home/hp/iacs5/me9x/public/input.dat", "r");
    fout = fopen("output.dat", "w");
    
    if ( (fin == NULL) || (fout == NULL))
    {
         printf("file open failure\n");
         exit(1);
    }

    lines = 0;
    printf("\n");
    fprintf(fout, "\n");

    while( fgets( text, 81, fin ) != NULL )
    {
           lines++;
           
           if ( lines % 2 != 0 )
           {
                sscanf(text, "%s%s%s", first, last, sale);    //no need for spaces between each %s.
                printf("Mr/Ms %s's sale was %s\n", last, sale);
           }
           else
           {
               sscanf(text, "%d%s", &number, car);    //use %d for integer and don't forget to use an ampersand!
                                                            Also, fgets is only ever reading data into text, not text2 as you had here previously
               printf("His/Her commision is %d\n", number);    //again, %d for integer
           }

    }
    
    getchar();
    return 0;
}

I find that whenever a program segfaults (crashes) on me, I look straight to the (s/f)scanf() lines for missing ampersands.

> Wow, much thanks man. It's the little things that mess me up
> I look straight to the (s/f)scanf() lines for missing ampersands.
You people need (NEED) to discover the magic of gcc options

Code:

gcc -W -Wall -ansi -pedantic -O2 foo.c
foo.c:6: warning: return type defaults to `int'
foo.c: In function `main':
foo.c:17: warning: implicit declaration of function `exit'
foo.c:34: warning: format argument is not a pointer (arg 3)
foo.c:35: warning: format argument is not a pointer (arg 2)
foo.c:39: warning: control reaches end of non-void function
foo.c:10: warning: 'number' might be used uninitialized in this function

It will tell you when you mess up your printf and scanf calls long before you're staring down the barrel of a segfault.

>You people need (NEED) to discover the magic of gcc options

Care to explain that for someone who has no idea what they're doing when it comes to the finer details of debugging?

I'm using dev-c++ on winxp if it makes a difference.

Code:

gcc -W -Wall -ansi -pedantic -O2 foo.c

All explained here

They're GCC commandline options, and will work wherever you install GCC in. Windows, *nix, your microwave oven processor, etc.

Yes, that's all well and good. But does this mean I have to compile/debug all my projects from the console now?

Ah, magic indeed. Cheers mate.

Though, I don't think I should be adding 'foo.c'