Finding segmentation fault in C - c

Question

I've commented all the code I thought was giving me an error, but I'm still getting it. this is my code:
int main(int argc, char **argv) {
// argc is the number of command line arguments, in our case there are two
// argv is an array of pointers, a[0] is the program name, a[1] will be sourcewav
// and a[2] should be destwav
FILE * source_file;
FILE * destination_file = fopen(argv[2], "w") ; // create destwav file
if (argc != 3) {
printf("Usage: requires two parameters: sourcewav and destwav");
exit(1);
}
//source_file = fopen(argv[1], "r+");
if (!source_file) { // pointer is null, file can't be opened
printf("Usage: %s sourcewav file cannot be opened\n", argv[0]);
exit(1);
}
printf("1");
remvocals(source_file, destination_file); // remove vocals
int closed_properly = fclose(source_file); // has source_file successfully closed?
if (closed_properly != 0) {
printf("Usage: %s sourcewav was not closed properly\n", argv[0]);
exit(1);
}
fclose(destination_file);
return 0;
}

Answer 1

you check sourcefile without initializing it. In addition, what remvocals does?

Answer 2

Move
if (argc != 3) {
printf("Usage: requires two parameters: sourcewav and destwav");
exit(1);
}
Before the declaration of your FILE pointers. Also, uncomment the line that initializes source_file. I think that you need argv[1] instead of argv[0] as the second argument of the printf placed in the body of the second and third ifs.

Answer 3

You haven't given enough information.
In your code, obvious concerns are;
1) destination_file is never checked to see if the fopen() succeeded. If destination_file is NULL, any operations on it (fprintf(), fclose()) will give undefined behaviour. The fopen() needs to be AFTER the check of argc, not before.
2) With the "source_file = fopen(argv[1], "r+")" statement commented, source_file is an uninitialised variable. Accessing its value - let alone passing it to I/O functions as a file argument - will give undefined behaviour.
3) You have a function called remvocals() which (presumably) is copying data from source_file to destination_file, but you have provided no information whatsoever about it. Even if the preceding two concerns are addressed, there are many things that function could be doing that introduce undefined behaviour.
Given all the above, it is quite possible your code is not even representative of your actual problem. You would be better off providing a small and complete sample that - when built - actually demonstrates your problem. Otherwise, people trying to help you are resorting to guesswork.

Answer 4

//source_file = fopen(argv[1], "r+");
if (!source_file) { // pointer is null, file can't be opened
printf("Usage: %s sourcewav file cannot be opened\n", argv[0]);
exit(1);
}
It looks to me, you forgot to uncomment this line:
//source_file = fopen(argv[1], "r+");
You also should move:
if (argc != 3) {
printf("Usage: requires two parameters: sourcewav and destwav");
exit(1);
}
Before the line where you fopen in this line:
FILE * destination_file = fopen(argv[2], "w") ; // create destwav file