C File handling in visual studio 2017 - c

Question

The file handling commands in Visual Studio seem to be different than normal. I'm currently learning the very basics of File Handling in C, but the commands don't seem to be working. This is what I've got right now -
#include <stdio.h>
int main()
{
int num;
FILE *fptr;
fptr = fopen("C:\\", "program.txt", "w");
if (fptr == NULL)
{
printf("Error!");
exit(1);
}
printf("Enter num: ");
scanf_s("%d", &num);
fprintf(fptr, "%d", num);
fclose(fptr);
return 0;
}
Here's the build output-
'fopen': too many actual parameters
warning C4013: 'exit' undefined; assuming extern returning int
error C4996: 'fopen': This function or variable may be unsafe. Consider using
fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
When I use fopen_s instead, like this fopen_s("C:\program.txt", "w"), it says-
'function': 'FILE **' differs in levels of indirection from 'char [15]'
'fopen_s': different types for formal and actual parameter 1
'fopen_s': too few arguments for call
'=': 'FILE *' differs in levels of indirection from 'errno_t'
I need some serious help.

Answer 1

You should open your file with either
FILE * f;
f= fopen("C:\\program.txt", "w");
or
FILE * f;
int err = fopen_s(&f, "C:\\program.txt", "w");
the latter takes FILE ** as an extra argument, and return error code (0 on success).

Answer 2

There is a extra comma , in fopen() which makes fopen() as three arguments, which is wrong & causing the error
'fopen': too many actual parameters
This
fptr = fopen("C:\\", "program.txt", "w"); /* fopen() expects 2 arguments */
replaces with
fptr = fopen("C:\\program.txt", "w");
You can disable below
'fopen': This function or variable may be unsafe. Consider using
fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
warning by
#pragma warning(disable:4996) /* use it before other headers */
Or use fopen_s().