makefile

A Makefile is a special file used by the `make` build automation tool to control the generation of executable programs and other non-source files from a computer program's source code. Here's a basic example and explanation of how a simple Makefile works: ### Simple Example Let's say you have a C project with two source files: `main.c` and `helper.c`, and you want to compile them into an executable called `program`. Your directory structure might look like this: ``` project/ ├── main.c └── helper.c ``` Here's a simple Makefile for this project: ```Makefile # Variables CC = gcc CFLAGS = -Wall -g TARGET = program OBJECTS = main.o helper.o # Default target all: $(TARGET) # Linking objects into the final executable $(TARGET): $(OBJECTS) $(CC) $(CFLAGS) -o $(TARGET) $(OBJECTS) # Compiling .c files into .o files main.o: main.c $(CC) $(CFLAGS) -c main.c helper.o: helper.c $(CC) $(CFLAGS) -c helper.c # Clean up build artifacts clean: rm -f $(TARGET) $(OBJECTS) ``` ### Explanation 1. **Variables**: The Makefile defines some variables at the beginning to avoid repetition: - `CC` specifies the compiler to use (`gcc` in this case). - `CFLAGS` specifies the flags to pass to the compiler (`-Wall -g` for all warnings and debug information). - `TARGET` is the name of the output executable (`program`). - `OBJECTS` lists the object files needed to build the target (`main.o` and `helper.o`). 2. **Default Target**: The `all` target is the default goal. When you run `make` without arguments, it will execute the rules for this target. Here, it depends on the `$(TARGET)`. 3. **Linking**: The rule for `$(TARGET)` depends on `$(OBJECTS)`. It uses the compiler to link the object files into the final executable. 4. **Compilation**: Each `.o` file has a rule that compiles the corresponding `.c` file. The `-c` flag tells `gcc` to compile the source file into an object file. 5. **Cleaning**: The `clean` target removes the generated binary and object files. You can run this by executing `make clean`. ### Using the Makefile To use this Makefile, place it in the same directory as your source files and run: ```sh make # This will build the 'program' executable make clean # This will remove the 'program' executable and object files ``` This is a very basic Makefile meant for illustrative purposes. Makefiles can be much more complex and are often used in larger projects with many source files, directories, and various build configurations.