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--- programming:make:basic_make_example [2021/02/04 14:44] – created peter
+++ programming:make:basic_make_example [2021/02/04 16:33] (current) – peter
@@ Line 1: / Line 1: @@
 ====== Programming - Make - Basic Make Example ======
+===== Basic Example =====
+==== Create a C program ====
+<file c hello.c>
+#include <stdio.h>
+int main()
+{
+  printf("Hello World");
+  return 0;
+}
+</file>
+----
+==== Create a Makefile ====
+<file bash Makefile>
+hello: hello.c
+</file>
+----
+==== Run Make ====
+<code bash>
+make
+</code>
+returns:
+<code bash>
+cc     hello.c   -o hello
+</code>
+<WRAP info>
+**NOTE:**  This compiles the C program.
+Most distributions will have cc pointing to the default C compiler.
+</WRAP>
+----
+==== Run Make Again ====
+<code bash>
+make
+</code>
+returns:
+<code bash>
+make: 'hello' is up to date.
+</code>
+<WRAP info>
+**NOTE:**  As nothing has changed, there is no need for Make to recompile the C program.
+To have the program be recompiled:
+  * Run **touch hello.c**, or
+  * Delete the compiled program, **rm hello**, or
+  * Modify the C program and run make again.
+</WRAP>
+----
+===== Enhanced Make =====
+Use variables within the Makefile:
+<file bash Makefile>
+CC=gcc
+CFLAGS=-g
+hello : hello.c
+</file>
+returns:
+<code bash>
+gcc -g    hello.c   -o hello
+</code>
+----
+===== Add further options to the Makefile =====
+<code bash>
+CC=gcc
+CFLAGS=-g
+# Comment next line to turn off optimization
+CFLAGS+=-O
+hello : hello.c
+</code>
+<WRAP info>
+**NOTE:**  The implicit rule being used is:
+<code bash>
+$(CC) $(CFLAGS) $(CPPFLAGS) hello.c -o hello
+</code>
+</WRAP>
+----
+===== Use an object =====
+Besides compiling, the Makefile can also link the object files:
+<file bash Makefile>
+hello : hello.o mylib.o
+hello.o : hello.c hello.h mylib.h
+mylib.o : mylib.c mylib.h
+</file>
+<WRAP info>
+**NOTE:**  Thanks to the default rules, this is all that is needed by Make.
+The make program is smart enough to see that it needs hello.o, it will go find the rule for hello.o and so on.
+Of course, additional lines can be added to control further what happens for the build process.
+</WRAP>