Using include guards and the undef directive

Author: georgecatalin

The Preprocessor/Include guards and undef directive/using_include_guards.c

@@ -0,0 +1,4 @@
+#ifndef _USING_INCLUDE_GUARDS_H
+#define _USING_INCLUDE_GUARDS_H  //when other file.h will use #include "using_include_guards.h" it will load this file only once, cause at a subsequent inclusing it is already activated
+    #include <stdio.h>
+#endif

The Preprocessor/Include guards and undef directive/using_include_guards.h

@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+
+int main(void)
+{
+    
+
+
+    return 0;
+}

The Preprocessor/Include guards and undef directive/using_undef.c

@@ -0,0 +1,8 @@
+#ifndef _USING_UNDEF_H
+    #define _USING_UNDEF_H
+
+    #define UNIX
+    #undef UNIX
+
+
+#endif