Initial commit of lecture code

LC21/cond.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/* We define one thing - we need not give it a value, but we can */
+#define BUILD1
+ 
+int main(void)
+{
+
+ 
+ printf ("\nThis code is common to all ");
+
+/* We check for the existance ob 'BUILD1' and act accordingly */
+
+#ifdef BUILD1  
+
+ printf ("\nWe had BUILD1 defined ");
+
+#else
+
+ printf ("\nBUILD1 was not defined ");
+
+#endif
+
+/* Can can see if somthing was not defined too */
+
+#ifndef BUILD2
+
+  printf ("\nBUILD2 was *NOT* defined ");
+
+#endif
+
+  printf ("\n\n");
+
+  return 0;
+
+}