Help! Problem with strings

I'm new to programming with C and I'm having problems with strings, pointers and structures. If someone could look at this code and tell me what's wrong, I'd greatly appreciate it.

Code:

struct FGrec_data{
	
	char *input_file;
	char *start_time;
	char *stop_time;
	char *output_file;
	char *output_path;
};

int main(int argc, char *argv[])                                                        

{	
       struct FGrec_data FGdt;
       parse_main_args(argc, argv, &FGdt);

......
}

int parse_main_args(int argc, char *argv[], struct FGrec_data *FGdata) 

{
       ....
       int i;
       for(i = (strlen(FGdata->output_file)-2); i > 0; i--) {
		if(FGdata->output_file[i] == 92) {
			strncpy(FGdata->output_path, FGdata->output_file, i);
			break;
		}
	}     

        //Why does this make my program crash? 
       ....
       ....
}

Print the output you get, as well the input to the function...

> char *input_file;
Compare with
char input_file[100];

In your case, you have no space allocated to any of the strings, so any string operation is going to blow up sooner or later.

It looks like you've not got any memory assigned to those pointers in your struct, so when you go about accessing them, so they're just pointing wildly into your process' heap.

So I should "malloc" all my strings?

If you're using pointers, yes you need to consider how the memory is allocated.

OK. Got it. Thank you!