演示1#include <stdio.h>void print_star(void){printf("*****************\n");}void print_welcome(void){printf("C language,welcome!\n");}void main(){print_star();print_welcome();print_star();getchar();}演示2#include "stdio.h"int sum(int i,int j){return(i + j);}void main(){int n1,n2;printf("input 2 numbers:\n");scanf("%d%d",&n1,&n2);printf("the sum = %d\n",sum(n1,n2));getchar();}演示3#include "stdio.h"int maxnum(int,int,int);main(){int a,b,c;printf("Please enter 3 numbers:\n");scanf("%d,%d,%d",&a,&b,&c);printf("Maxnum is %d\n",maxnum(a,b,c));return 0;}int maxnum(int x,int y,int z) {int max=x;if(y>max)max = y;if(z>max)max = z;return max;}演示4#include <stdio.h>int s1(int n){int j,s;s=0;for(j=1;j<=n;j++)s=s+j;return s;}int sum(int n){int i,s=0;for(i=1;i<=n;i++)s=s+s1(i);return s;}void main(){int n;printf("n:");scanf("%d",&n);printf("s=%d\n",sum(n)); }演示5#include <stdio.h>void func(int n){int i;for(i=n-1;i>=1;i--)n=n+i;printf("n=%d\n",n);}void main(){int n;printf("Input n:");scanf("%d",&n);func(n);printf("n=%d\n",n);}演示6#include <stdio.h>void swap(int a,int b){int temp;temp=a;a=b;b=temp;printf("swap : a=%d,b=%d\n",a,b); }void main(){int a,b;a=3;b=10;swap(a,b);printf("a=%d,b=%d\n",a,b);}演示7#include <stdio.h>int func(int a,int b){int c;c=a+b;return c;}void main(){int x=6,y=7,z=8,r;r=func((x--,y++,x+y),z--);printf("%d\n",r);}演示8#include <stdio.h>max(float x,float y){return x>y? x:y;}void main(){printf("%d\n",max(2,3.5)); }演示9#include <stdio.h>int sum(int n){int i,s=0;for(i=0;i<=n;i++)s=s+i;return s;}void main(){int m,sn;scanf("%d",&m);sn=sum(m);printf("the sum is %d\n",sn); }演示10#include <stdio.h>void swap(int x,int y);int main(){int a,b;printf("input 2 numbers :\n"); scanf("%d,%d",&a,&b);printf("input number is:a=%d,b=%d \n",a,b);swap(a,b);printf("input 2 numbers is:a=%d,b=%d\n",a,b);return 0;}void swap(int x,int y){int temp;temp = x;x = y;y = temp;printf("swap number is : x = %d,y = %d \n",x,y);}演示11#include "stdio.h"#define K 3#define N 5long f2(int n,int k){long power = n;int i;for(i=1;i<k;i++)power *=n;return power;}long f1(int n,int k){long sum = 0 ;int i;for(i=1;i<=n;i++)sum = sum + f2(i,k);return sum;}int main(void){printf("sum of %d power of integer from 1 to %d = ",K,N); printf("%ld\n",f1(N,K));return 0;}演示12#include <stdio.h>int min(int a,int b);int main(void){int j,k,mininum;printf("input 2 integers:");scanf("%d,%d",&j,&k);mininum = min(j,k);printf("\n of the two values %d and %d,the mininum is %d\n",j,k,mininum); return 0;}int min(int a,int b){if(a<b)return a;elsereturn b;}演示13#include <stdio.h>int func(int a,int b);void main(){int k=4,m=1,p;p=func(k,m);printf("%d\n",p);}int func(int a,int b){int m=0,i=2;i+=m+1;m=i+a+b;return m;}演示14#include <stdio.h>int max(int x,int y){int z;z=x>y?x:y;return z;}void main()extern int A,B; //声明外部变量printf("%d\n",max(A,B));}int A=13,B=-8; //定义外部变量演示15#include <stdio.h>int f1(int xb){extern int xa;return (xa*xb);}int main(void){extern int xb;int xa = 5;printf("xa=%d,xb=%d,result=%d",xa,xb,f1(xa)); return 0;}int xa = 3,xb = 4;演示16#include <stdio.h>void num(){extern int x,y;int a=15,b=10;x=a-b;y=a+b;}int x,y;void main(){int a=7,b=5;x=a+b;y=a-b;num();printf("%d,%d\n",x,y);}演示17#include <stdio.h>void main()void swap();extern int a,b;a=3;b=10;swap();printf("a=%d,b=%d\n",a,b);}int a,b;void swap(){int temp;temp=a;a=b;b=temp;}演示18#include <stdio.h>void auto_static(void){int var_auto = 0;static int var_static = 0;printf("var_auto = %d,var_static = %d\n",var_auto++,var_static++); }void main(){int i;for (i=0;i<3;i++)auto_static();}演示19#include <stdio.h>void swap(int x,int y){int t;t=x;x=y;y=t;}void main(){int a,b;scanf("%d,%d",&a,&b);swap(a,b);printf("%d,%d\n",a,b);}----------------------------------------------------------------------------------------------------------#include <stdio.h>int x,y;void swap(int ，,int){int t;t=x;x=y;y=t;}void main(){scanf("%d,%d",&x,&y);swap(x,y);printf("%d,%d\n",x,y);}#include <stdio.h>int x,y;void swap(int x,int y){int t;t=x;x=y;y=t;}void main(){scanf("%d,%d",&x,&y);swap(x,y);printf("%d,%d\n",x,y);}----------------------------------------------------------------------------------------------------------------------演示20#include <stdio.h>int fac(int n){static int f=1;f=f*n;return f;}void main(){int i;for(i=1;i<=5;i++)printf("%d!=%d\n",i,fac(i));}演示21#include "stdio.h"int main(void){int a = 2;int p = a;printf("%d\n",a);{int a =7;printf("%d\n",a);printf("%d\n",p);}printf("%d\n",++a);return 0;}演示22#include <stdio.h>int func(int a,int b);void main(){int k=4,m=1,p;p=func(k,m);printf("%d,",p);p=func(k,m);printf("%d\n",p); }int func(int a,int b){static int m=0,i=2;i+=m+1;m=i+a+b;return m;}演示23#include <stdio.h>f(int n){int c;if(n==6)c=1;elsec=(f(n+1)+1)*2;return c;}void main(){printf("%d\n",f(1));}演示24#include <stdio.h>long power(int n){long f;if(n>1)f=power(n-1)*n;elsef=1;return f;}main(){int n;long x;printf("input an integer number:\n"); scanf("%d",&n);x=power(n);printf("%d!=%ld\n",n,x);getchar();}演示25#include <stdio.h>int fact(){static int i=5;if(i==0) return 1;else{i--;return (i+1)*fact();}}void main(){printf("fact=%d\n",fact()); }演示26#include <stdio.h>int fun(int k);int w=3;void main(){int w=10;printf("%d\n",fun(5)*w);}int fun(int k){if(k==0) return w;return(fun(k-1)*k);}演示27#include <stdio.h>int fac(int n){register int i,f=1;for(i=1;i<=n;i++)f=f*i;return f;}main(){int i;for(i=1;i<=5;i++)printf("%d!=%d\n",i,fac(i)); }演示28#include <stdio.h>age(int n){int c;if(n==1)c=10;elsec=age(n-1)+2;return c;}void main(){printf("%d\n",age(5));}演示29#include <stdio.h>#define PI 3.14#define circuit(r) 2*PI*r#define area(r) PI*r*rvoid main(){float ra,c,a;scanf("%f",&ra);c=circuit(ra);a=area(ra);printf("ra=%f,c=%f,a=%f",ra,c,a);}汉诺塔（演示30）#include "stdio.h"void move(int,char,char,char);int main(void){int n;printf("input n disk on tower A:\n");scanf("%d",&n);move(n,'A','B','C');getchar();return 0;}void move(int n,char a,char b,char c){static int step=1;if(n==1){printf("step %d :move disk form %c -> %c\n",step++,a,c); }else{move(n-1,a,c,b);move(1,a,b,c);move(n-1,b,a,c);}}演示31#define LETTER 1#include "stdio.h"void main(){char str[20]="C Language",c;int i;i=0;while((c=str[i])!='\0'){i++;#if LETTERif(c>='a'&&c<='z')c=c-32;#elseif(c>='A'&&c<='Z')c=c+32;#endifprintf("%c",c);}}#include <stdio.h>long f(int n){if(n==1||n==2)return 1;elsereturn f(n-1)+f(n-2);}void main(){long n;printf("input n:\n");scanf("%d",&n);printf("the number is %d\n",f(n)); }。