Can't compile with time- and clock-related functions C++ - c++

Question

I starting my first GNU project based on another GNU project to improve upon it and change the implementation.
I tried to implement my own build method, but time- and clock-related functions broke my build.
I've read a lot of questions on Stack Overflow, but I very confused with the three libraries chrono, ctime and time.h.
This is the build errors:
/src/gamed/Logger.cpp
#include "Logger.h"
#include <errno.h>
#include <string.h>
#include <stdarg.h>
#include <time.h>
const std::string Logger::CurrentDateTime()
{
time_t now = time(0);
struct tm tstruct;
char buf[80];
tstruct = *localtime(&now);
strftime(buf, sizeof(buf), "%Y-%m-%d %X", &tstruct);
return buf;
}
Error: time, localtime and strftime identifier not found
/src/gamed/Packets.h
#ifndef _PACKETS_H
#define _PACKETS_H
#include <time.h>
#include <cmath>
#include <set>
{...}
class GamePacket : public BasePacket {
public:
GamePacket(uint8 cmd = 0, uint32 netId = 0) : BasePacket(cmd, netId) {
buffer << (uint32)clock();
}
};
Error: clock identifier not found
/src/gamed/Pathfinder.cpp
#include "Logger.h"
#include "Pathfinder.h"
#include "Map.h"
#include "AIMesh.h"
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <chrono>
#include "Logger.h"
#include "Minion.h"
#include "Champion.h"
Map * Pathfinder::chart = 0;
auto g_Clock = std::clock();
Error: clock isn't member of std
What am I doing wrong?

Answer 1

I very confused with the three libraries chrono, ctime and time.h.
There's only 2 libraries in that sentence. <chrono> is part of the c++ standard library and was introduced in c++11 version of the standard. None of your code seem to use anything from <chrono>. <time.h> is part of the c standard library. <ctime> is a header in c++ standard library which wraps <time.h> inside std namespace instead of global namespace which is the only "namespace" in c.
#include <time.h>
// ....
auto g_Clock = std::clock();
Error: clock isn't member of std
You included the c header but try to refer to the std namespace. That is not correct. Include <ctime> instead so that clock will be in std.
#include <time.h>
// ...
time_t now = time(0);
Error: time (...) identifier not found
At a glance, your code there seems correct. Double check that's actually the code you're compiling and getting the errors from. Here's simplified version of that function which compiles fine http://coliru.stacked-crooked.com/a/664f568053103f32
Stylewise, I wouldn't recommend mixing <cXXX> and <XXX.h> headers. Pick one.

Answer 2

Solved!
The problem is the project use enet library, and has time.h, renaming file to enet_time.h the build work great (It's temporary fix, I think is better using namespaces).
Thanks to all and sorry for the inconvenients, I learn more of wrapping C libraries into C++ thanks to all responses.
A greeting

Answer 3

In C++ you should use the "c" prefix on all your C-library #includes.
So #include <time.h> should become: #include <ctime>.
But note that when you use #include <ctime> everything in time.h will now be in the std namespace.
So clock() must become std::clock().
For more info see: http://www.parashift.com/c++-faq/include-c-hdrs-system.html