<29> "Mastering" #if-#else conditional compilation Instructions +

"Mastering" #if-#else conditional compilation directives

#include <stdio.h>#defineScore 99intMainintargcConst Char*argv[]) {       //Traditional Way//int score =;//    //determine which grade the score belongs to//if (score<60) {//printf ("e\n");//}else if (score<=69) {//printf ("d\n");//}else if (score<=79) {//printf ("c\n");//}else if (score<=89) {//printf ("b\n");//}else{//printf ("a\n");//    }     #ifScore < 60printf ("e\n");#elifScore <= 69printf ("d\n");#elifScore <= 79printf ("c\n");#elifScore <= 89printf ("b\n");#elseprintf ("a\n");#endif        return 0;}

Summary: Comments are not compiled, conditional compilation is partially compiled

"Mastering" #ifdef conditional compilation Instructions

conditional Compilation Directives      1 #if  #elif  #else  #endif     2) #ifdef  

#include <stdio.h>#defineDEBUG1 1#defineDEBUG2 0intMainintargcConst Char*argv[]) {        intA =0; //ifdef detect if a macro is defined#ifdef DEBUG//The DEBUG system already defines the macro.A =Ten; #else a=10000; #endifprintf ("%d\n", a); //Ifndef detect if macros are defined ifndef if not defined#ifndef DEBUG2 a= -; #elsea= -1; #endifprintf ("%d\n", a); return 0;}

Ten-1

<29> "Mastering" #if-#else conditional compilation Instructions +