In CMake, the check_library_exists function is used to check for the existence of a library in the system. It takes three arguments: the name of the library, the symbol to look for in the library, and a variable to store the result. When the function is called, it will attempt to link against the specified library and check if the symbol is available in the library.
If the library is found and the symbol is present, the specified variable will be set to TRUE. Otherwise, it will be set to FALSE. This can be useful for conditional compilation, where certain code should only be compiled if a specific library is available on the system.
An example usage of check_library_exists in CMake would be:
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check_library_exists(m library_function LIBRARY_FOUND) if(LIBRARY_FOUND) message("Library found") # Additional actions if the library is found else() message("Library not found") # Additional actions if the library is not found endif() |
Overall, the check_library_exists function provides a way to dynamically check for the presence of libraries in a CMake project, allowing for more flexible and robust build configurations.
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How to check for the existence of a library using check_library_exists in cmake?
To check for the existence of a library using check_library_exists in CMake, you can follow these steps:
- Use the check_library_exists function in your CMakeLists.txt file to check for the existence of a library. The syntax of the function is as follows:
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check_library_exists(<library_name> <function_name> <variable_name>)
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- Replace with the name of the library you want to check for, with the name of a function or symbol within the library that you want to check for, and with the name of the variable that will store the result of the check.
- For example, if you want to check for the existence of the pthread library and the function pthread_create, you can use the following code:
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check_library_exists(pthread pthread_create HAVE_PTHREAD_CREATE)
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- This will set the variable HAVE_PTHREAD_CREATE to 1 if the library and function are found, and to 0 if they are not found.
- You can then use the result of the check in your CMakeLists.txt file to conditionally include or exclude certain build steps or options based on the availability of the library.
- For example, you can use an if statement to check the value of the variable HAVE_PTHREAD_CREATE like this:
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if (HAVE_PTHREAD_CREATE) message("pthread library and pthread_create function found") # Add build steps or options that require the library here else() message("pthread library or pthread_create function not found") # Add alternative build steps or options here endif() |
By following these steps, you can use the check_library_exists function in CMake to check for the existence of a library and take appropriate actions based on the result of the check.
What is the recommended practice for using check_library_exists in cmake?
The recommended practice for using check_library_exists in CMake is as follows:
- Use the check_library_exists function to check for the existence of a specific library in the system. This function takes the following arguments: library_name, function_name, and variable_name.
- First, use the find_library function to locate the library in the system. This function should be used before calling check_library_exists.
- After locating the library, use check_library_exists with the appropriate library_name and function_name to check if a specific function exists within the library.
- The result of check_library_exists will be stored in the variable specified by variable_name. This variable can then be used in conditional statements or other parts of the CMakeLists.txt file.
- It is recommended to use the REQUIRED option with the find_library function to ensure that CMake generates an error if the library cannot be found. This helps to provide more informative feedback to the user.
Overall, using check_library_exists in combination with find_library is a good practice to ensure that the required libraries and functions are available in the system before proceeding with the build process.
What is the return value of check_library_exists in cmake?
The return value of check_library_exists in CMake is a boolean value (true/false). It returns true if the specified library is found, and false if it is not found.
How to conditionally use check_library_exists in cmake based on platform or compiler?
To conditionally use check_library_exists in CMake based on platform or compiler, you can use an if statement with the appropriate condition.
For example, to check for the existence of a library only on Windows platform, you can use the following code:
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if(WIN32) check_library_exists(library_name function_name "" HAS_LIBRARY) if(HAS_LIBRARY) target_link_libraries(your_target_name library_name) else() message(WARNING "Library not found") endif() endif() |
Similarly, you can use CMAKE_C_COMPILER_ID variable to check for a specific compiler, for example:
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if(CMAKE_C_COMPILER_ID STREQUAL "GNU") check_library_exists(library_name function_name "" HAS_LIBRARY) if(HAS_LIBRARY) target_link_libraries(your_target_name library_name) else() message(WARNING "Library not found") endif() endif() |
By using such conditional statements, you can control when check_library_exists is executed based on the platform or compiler being used.
