header-files – Page 6

How to make g++ search for header files in a specific directory?

April 8, 2023 by Tarik

A/code.cpp #include <B/file.hpp> A/a/code2.cpp #include <B/file.hpp> Compile using: g++ -I /your/source/root /your/source/root/A/code.cpp g++ -I /your/source/root /your/source/root/A/a/code2.cpp Edit: You can use environment variables to change the path g++ looks for header files. From man page: Some additional environments variables affect the behavior of the preprocessor. CPATH C_INCLUDE_PATH CPLUS_INCLUDE_PATH OBJC_INCLUDE_PATH Each variable’s value is a list of … Read more

How can I create C header files [closed]

March 28, 2023 by Tarik

Open your favorite text editor Create a new file named whatever.h Put your function prototypes in it DONE. Example whatever.h #ifndef WHATEVER_H_INCLUDED #define WHATEVER_H_INCLUDED int f(int a); #endif Note: include guards (preprocessor commands) added thanks to luke. They avoid including the same header file twice in the same compilation. Another possibility (also mentioned on the … Read more

How to read a CMake Variable in C++ source code

March 27, 2023 by Tarik

The easiest way to do this, is to pass the LIBINTERFACE_VERSION as a definition with add_definition: add_definitions( -DVERSION_LIBINTERFACE=${LIBINTERFACE_VERSION} ) However, you can also create a “header-file template” and use configure_file. This way, CMake will replace your @LIBINTERFACE_VERSION@. This is also a little more extensible because you can easily add extra defines or variables here… E.g. … Read more

How to create two classes in C++ which use each other as data?

March 23, 2023 by Tarik

You cannot have two classes directly contain objects of the other type, since otherwise you’d need infinite space for the object (since foo has a bar that has a foo that has a bar that etc.) You can indeed do this by having the two classes store pointers to one another, though. To do this, … Read more

default parameters in .h and .cpp files [duplicate]

March 12, 2023 by Tarik

Defaults should always go in the header file, if the function is declared in a header file. This is because the compiler will use the header file for ALL compile units that use your class [unless you are being “naughty” and don’t use the header file everywhere it should go]. Since the compiler adds default … Read more

Difference between and ?

March 11, 2023 by Tarik

<string.h> contains old functions like strcpy, strlen for C style null-terminated strings. <string> primarily contains the std::string, std::wstring and other classes.

Writing function definition in header files in C++

March 10, 2023 by Tarik

If the function is small (the chance you would change it often is low), and if the function can be put into the header without including myriads of other headers (because your function depends on them), it is perfectly valid to do so. If you declare them extern inline, then the compiler is required to … Read more

Can I write C++ code without headers (repetitive function declarations)?

March 4, 2023 by Tarik

Use Lzz. It takes a single file and automatically creates a .h and .cpp for you with all the declarations/definitions in the right place. Lzz is really very powerful, and handles 99% of full C++ syntax, including templates, specializations etc etc etc. Update 150120: Newer C++ ’11/14 syntax can only be used within Lzz function … Read more

undefined reference when calling inline function

March 1, 2023 by Tarik

According to the manual, passing -std=gnu11 enables C99 instead of GNU inline semantics. This means inline, static inline and extern inline all behave differently. In particular, inline expects an external definition in a separate translation unit (which you can provide without duplicating the definition – see this answer).

How to use the tool include-what-you-use together with CMake to detect unused headers?

February 28, 2023 by Tarik

CMake 3.3 introduced the new target property CXX_INCLUDE_WHAT_YOU_USE that can be set to the path of the program include-what-you-use. For instance this CMakeLists.txt cmake_minimum_required(VERSION 3.3 FATAL_ERROR) add_executable(hello main.cc) find_program(iwyu_path NAMES include-what-you-use iwyu REQUIRED) # If using CGAL<3.18, you remove REQUIRED and use # if(NOT iwyu_path) # message(FATAL_ERROR “Could not find the program include-what-you-use”) # endif() … Read more