![C语言经典程序100例：[5]41--50](https://search.52zhanxing.com/aiimages/C语言经典程序100例：[5]41--50.png)
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【程序41】题目：学习static定义静态变量的用法 1.程序分析：2.程序源代码：#include "stdio.h"#include "conio.h"varfunc(){ int var=0; static int static_var=0; printf("\40:var equal %d \n",var); printf("\40:static var equal %d \n",static_var); printf("\n"); var++; static_var++;}void main(){ int i; for(i=0;i<3;i++) varfunc(); getch();}==============================================================【程序42】题目：学习使用auto定义变量的用法1.程序分析： 2.程序源代码：#include "stdio.h"#include "conio.h"main(){ int i,num; num=2; for(i=0;i<3;i++) { printf("\40: The num equal %d \n",num); num++; { auto int num=1; printf("\40: The internal block num equal %d \n",num); num++; } } getch();}==============================================================【程序43】题目：学习使用static的另一用法。 1.程序分析：2.程序源代码：#include "stdio.h"#include "conio.h"main(){ int i,num; num=2; for(i=0;i<3;i++) { printf("\40: The num equal %d \n",num); num++; { static int num=1; printf("\40:The internal block num equal %d\n",num); num++; } } getch();}==============================================================【程序44】题目：学习使用external的用法。1.程序分析：2.程序源代码：#include "stdio.h"#include "conio.h"int a,b,c;void add(){ int a; a=3; c=a+b;}void main(){ a=b=4; add(); printf("The value of c is equal to %d\n",c); getch();}==============================================================【程序45】题目：学习使用register定义变量的方法。1.程序分析：2.程序源代码：#include "stdio.h"#include "conio.h"void main(){ register int i; int tmp=0; for(i=1;i<=100;i++) tmp+=i; printf("The sum is %d\n",tmp); getch();}==============================================================【程序46】题目：宏#define命令练习(1) 1.程序分析：2.程序源代码：#include "stdio.h"#include "conio.h"#define TRUE 1#define FALSE 0#define SQ(x) (x)*(x)void main(){ int num; int again=1; printf("\40: Program will stop if input value less than 50.\n"); while(again) { printf("\40:Please input number==>"); scanf("%d",&num); printf("\40:The square for this number is %d \n",SQ(num)); if(num>=50) again=TRUE; else again=FALSE; } getch();}==============================================================【程序47】题目：宏#define命令练习(2)1.程序分析： 2.程序源代码：#include "stdio.h"#include "conio.h"/*宏定义中允许包含两道衣裳命令的情形，此时必须在最右边加上"\"*/#define exchange(a,b) { \ int t;\ t=a;\ a=b;\ b=t;\ }void main(void){ int x=10; int y=20; printf("x=%d; y=%d\n",x,y); exchange(x,y); printf("x=%d; y=%d\n",x,y); getch();}==============================================================【程序48】题目：宏#define命令练习(3) 1.程序分析：2.程序源代码：#define LAG >#define SMA <#define EQ ==#include "stdio.h"#include "conio.h"void main(){ int i=10; int j=20; if(i LAG j) printf("\40: %d larger than %d \n",i,j); else if(i EQ j) printf("\40: %d equal to %d \n",i,j); else if(i SMA j) printf("\40:%d smaller than %d \n",i,j); else printf("\40: No such value.\n"); getch();}==============================================================【程序49】题目：#if #ifdef和#ifndef的综合应用。1. 程序分析：2.程序源代码：#include "stdio.h"#include "conio.h"#define MAX#define MAXIMUM(x,y) (x>y)?x:y#define MINIMUM(x,y) (x>y)?y:xvoid main(){ int a=10,b=20;#ifdef MAX printf("\40: The larger one is %d\n",MAXIMUM(a,b));#else printf("\40: The lower one is %d\n",MINIMUM(a,b));#endif#ifndef MIN printf("\40: The lower one is %d\n",MINIMUM(a,b));#else printf("\40: The larger one is %d\n",MAXIMUM(a,b));#endif#undef MAX#ifdef MAX printf("\40: The larger one is %d\n",MAXIMUM(a,b));#else printf("\40: The lower one is %d\n",MINIMUM(a,b));#endif#define MIN#ifndef MIN printf("\40: The lower one is %d\n",MINIMUM(a,b));#else printf("\40: The larger one is %d\n",MAXIMUM(a,b));#endif getch();}==============================================================【程序50】题目：#include 的应用练习 1.程序分析：2.程序源代码：test.h 文件如下:#define LAG >#define SMA <#define EQ ==主文件如下:#include "test.h" /*一个新文件50.c，包含test.h*/#include "stdio.h"#include "conio.h"void main(){ int i=10; int j=20; if(i LAG j) printf("\40: %d larger than %d \n",i,j); else if(i EQ j) printf("\40: %d equal to %d \n",i,j); else if(i SMA j) printf("\40:%d smaller than %d \n",i,j); else printf("\40: No such value.\n"); getch();}