File I/O Uninitialised Variable Problem - C Program - c

Question

I have the following code and when I try to run it, I get the following warning:
warning: variable 'myfile' is uninitialized when used here [-Wuninitialized]
myfile = fetch_file(myfile, argc, argv);
note: initialize the variable 'myfile' to silence this warning
FILE *myfile;
I have been trying to find out how to fix the warning but haven't been successful.
#include <stdio.h>
#include <stdlib.h>
#define LINE_SIZE 300
FILE * fetch_file(FILE *myfile, int argc, char *argv[1])
{
if (argc == 1)
{
printf("Error, not enough commandline arguments.");
exit(0);
}
myfile = fopen (argv[1], "r");
if (myfile == NULL)
{
printf("\nNo file named %s was found.", argv[1]);
exit(0);
}
else
{
printf("%s was successfully opened", argv[1]);
}
return myfile;
}
void print_file(FILE *the_file, char *line, int size)
{
int count = 0;
while (fgets(line, size, the_file) != NULL)
{
printf("%s", line);
count++;
}
fclose(the_file);
printf("\nThere are %d lines\n", count);
}
int main (int argc, char *argv[])
{
FILE *myfile;
char line[LINE_SIZE];
myfile = fetch_file(--> myfile <-- , argc, argv); <----------- (warning)
print_file(myfile, line, LINE_SIZE);
return 0;
}
Ps: I'm fairly new to asking questions on this website, so if there is any way I can improve my questions and code, feel free to criticise me...

Answer 1

You want this:
FILE *fetch_file(int argc, char *argv[1])
{
if (argc == 1)
{
printf("Error, not enough commandline arguments.");
exit(0);
}
FILE *myfile = fopen (argv[1], "r");
...
}
int main (int argc, char *argv[])
{
FILE *myfile;
char line[LINE_SIZE];
myfile = fetch_file(argc, argv);
...
}
It is pointless to pass the myfile parameter to fetch_file.
The reason for the warning is that you pass an uninitialized value to a function:
This simple code reproduces this exact problem:
int foo(int bar)
{
bar = 2;
return bar * 2;
}
int main (int argc, char *argv[])
{
int kwork; // kwork is not initialized
foo(kwork); // here you pass an uninitialized value
// which the foo function cannot use in a useful manner
}