Weird fopen() segfault

Ok, i've googled this and searched on the forums already and didn't find anything that really helped. This code is segfaulting right after the sleep() call.

Code:

#include <stdio.h>
#include <string.h>
	
int main(int argc, char *argv[]) {
	FILE *fp, *ofp;
	char *mode = 'r';
	fprintf(stderr, "Sleeping\n");
	printf("Trying to open %s\n",argv[1]);
	sleep(3);
	if ((fp = fopen("index.html", mode)) == EOF) { //tried argv[1] where index.html is too
		fprintf(stderr, "File Not Found\n");
		exit(1);
	}
}

Code:

./getprx index.html
Sleeping
Segmentation fault

Index.html exists in the directory the program is being run, I tried using the full path also that didn't help.

Try this:

if ((fp = fopen("index.html", 'r')) == EOF)

By getting rid of the pointer to r and just using r.

Todd

Don't you get warnings about converting integers to pointers without a cast? Have you tried

Code:

char *mode = "r";

Also, I wouldn't use EOF as a condition to tell if the file opened properly.

If you enable a minimal level of warnings when you compile that code, it would tell you that you are assigning an integer into a pointer (char *mode = 'r'). This will directly cause a segfault when the fopen() function tries to determine what your mode is, and tries to read memory at address 114 (the ascii-value of 'r').

--
Mats

Read documentation with regard to the parameters, the return value, and the noteworthy behavior of the functions you plan on using.

Yeah that was actually a really stupid mistake. I don't know C very well, just migrating over from Java and was expecting the compiler to give me more errors. I should probably turn that up so I don't get lost in runtime errors like this.

Java protects you from yourself a lot more effectively than C does. C will let you do all kinds of stupid things without even blinking, since it assumes you know what you're doing and just need a safety net for some things.

Try this, it may solve your problem ..
if ((fp = fopen("index.html", 'r')) == NULL)

Originally Posted by krishna

Try this, it may solve your problem ..
if ((fp = fopen("index.html", 'r')) == NULL)

No, it will not

Code:

if ((fp = fopen("index.html", "r")) == NULL)

should be

thanks for this correction