On Tuesday, 20 February 2018 at 14:56:54 UTC, Chris M. wrote:
I'm doing this mainly for experimentation, but the following
piece of code gives all sorts of errors. Hangs, segfaults or
prints nothing and exits
import std.stdio;
import core.stdc.stdlib;
void main()
{
auto f = cast(File *) malloc(File.sizeof);
*f = File("test.txt", "r");
(*f).readln.writeln;
// freeing is for chumps
}
I could have sworn I've done something similar recently and it
worked, unfortunately I can't remember what the case was.
This is what gdb gave me on a segfault
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7a56c32 in
_D2rt5minfo__T17runModuleFuncsRevSQBgQBg11ModuleGroup8runDtorsMFZ9__lambda1ZQCkMFAxPyS6object10ModuleInfoZv ()
from /usr/lib64/libphobos2.so.0.78
So it looks like it's reaching the end of main. Past that I
can't tell what's going on. Ideas?
File * is a C standard library type. You mixed the C standard
library and D standard library in a way that would not work.
The correct way to initialize a File*:
void main()
{
import core.stdc.stdlib;
auto F = fopen("test.txt", "r");
scope_exit(fclose(f));
//Reading from the file:
char[100] str;
fgets(&s[0], s.length, f);
}
Honestly speaking though you should avoid using the C library
when you can use th D standard library.
You can read more on the C standard library and how to use it
here:
http://en.cppreference.com/w/c/io
