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+--- Thread: What's wrong with this code? (/showthread.php?tid=17592)
What's wrong with this code? - Fiel - 2009-10-14
Code:
#include <stdio.h>
struct myStruct
{
int a;
int b;
};
int main(void)
{
FILE* foo;
struct myStruct bar;
foo = fopen("foobar.txt", "rb");
fread(&bar.a, 4, 1, foo);
fclose(foo);
printf("%d\n", bar.a);
return 0;
}The program generates a runtime exception when executing the fread() command. What's the correct way to do this?
What's wrong with this code? - Orit - 2009-10-14
C has no exceptions.
Please add the following after fopen:
Code:
if (foo <= 0)
perror("fopen failed");What's wrong with this code? - Fiel - 2009-10-14
This program is just to illustrate a point, not to bother with exception handling.
Windows generates the exception.
What's wrong with this code? - Orit - 2009-10-14
I know, but the exception could happen if the fopen failed. Are you quite sure it succeeded?
What's wrong with this code? - Fiel - 2009-10-14
Ah, I see what you're saying. My bad.
Yes, I'm 100% sure it succeeded. I use a function "safe_fopen" which always checks for NULL when opening a file.
What's wrong with this code? - Orit - 2009-10-14
Are the arguments to fread correct?
ISTR all the "f" family of functions having the FILE* as first argument, but I shamefully admit I have no C compiler on this, my mapling machine, so I can't make sure.
What's wrong with this code? - Tempus - 2009-10-14
I can recreate the error, but only when fopen() fails. If the file exists and opens correctly, I don't get any runtime exception.