如何配置CMake的add_executable()引入父目录同级子目录下的file2.h？

Hey there! Let's break down your two CMake questions with practical, easy-to-follow examples.

First off, you'll need to do two key things: tell CMake where to find the header files from that sibling directory, and include any source files from there that need to be compiled into your executable.

Let's use a concrete directory structure to make this tangible:

my_project/
├── my_app/
│   ├── main.cpp
│   └── CMakeLists.txt  # This is the file we'll edit
└── common_utils/
    ├── helper.h
    └── helper.cpp

Here's how to set up the my_app/CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project(MyApp)

# Get the path to the sibling common_utils directory
set(COMMON_UTILS_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../common_utils")

# Create the executable, including the source file from the sibling directory
add_executable(MyApp main.cpp "${COMMON_UTILS_DIR}/helper.cpp")

# Tell the executable where to find the header files (modern CMake approach)
target_include_directories(MyApp PRIVATE "${COMMON_UTILS_DIR}")

Quick notes: #

• CMAKE_CURRENT_SOURCE_DIR refers to the folder where the current CMakeLists.txt lives, so ../common_utils jumps up one level and into the sibling directory.
• target_include_directories with PRIVATE ensures this header path only applies to MyApp (it won't leak to other targets that might depend on it). This is the recommended modern CMake practice over global include_directories().
• If the sibling directory only has header files (no .cpp files to compile), you can skip adding the .cpp to add_executable()—just keep the target_include_directories line so your code can #include those headers.

First, let's assume a typical project structure where file2.h lives in a separate include directory:

my_project/
├── src/
│   ├── main.cpp
│   └── CMakeLists.txt
└── include/
    └── file2.h

A quick clarification: Header files don't get compiled directly, so technically you don't need to list file2.h in add_executable(). However, adding it has two benefits: your IDE will recognize it as part of the project, and CMake will trigger a recompile if the header changes.

Here's the setup for src/CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project(MyProject)

# Define the path to the include directory
set(INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../include")

# Create the executable—we include file2.h here for IDE visibility and rebuild triggers
add_executable(MyExecutable main.cpp "${INCLUDE_DIR}/file2.h")

# Tell the executable where to find the header files
target_include_directories(MyExecutable PRIVATE "${INCLUDE_DIR}")

Now in main.cpp, you can simply write:

#include "file2.h"

If file2.h were in the same directory as main.cpp, you could skip the target_include_directories line and just list the header in add_executable() (if desired)—CMake will automatically find it in the current source directory.

内容的提问来源于stack exchange，提问作者Ben Schroeder