"errno_t was not declared in this scope" error

[thor36]

Greetings all !
I have a piece of sample code from an open library. It was supposedly written for msvs, but I am using codeblocks with mingw compiler on a windows 7 machine.

The (so I think) relevant piece of code is:

#include <iostream>
#include <errno.h>
#include <stdio.h>

errno_t err;

The error I get is :
error: 'errno_t' was not declared in this scope|

I searched online for what to do with errno_t, but all I figured out is about its purpose. What can I do to fix this and make the program work ? Thank you.
Kind regards, T

[LB]

http://www.cplusplus.com/reference/cerrno/errno/
http://en.cppreference.com/w/cpp/header/cerrno
I don't think errno_t exists. Instead, you should try decltype(errno)

[thor36]

Thank you for reply. But I would like to ask for further assistance.

I wrote this:

typedef decltype(errno) err;

and at the line with code :
err = fopen(&infile, infilename, "r");

I get error:
error: expected unqualified-id before '=' token|

What am I missing and not doing right ?
Thank you, T

[LB]

By using the typedef keyword, you make err a type instead of a variable.

However, in this case since you immediately assign to the variable, you can forget about the data type and let the compiler figure it out for you: auto err = fopen(&infile, infilename, "r");

Though, really, if you are going to use C++ at all, you should use it completely and ignore C:

if(std::ifstream infile {infilename})
{
    //success
}
else
{
    //error
}

There's generally no use for detailed error information except in specialized cases. For the most part, your only concern is whether you could open the file or not.