C语言例题 [未完待续...]

//递归求字符串长度
strlen (char *s){
	if(*s=='\0')	return (0);
	else			return (1+strlen(s+1));
}
main(){
	char a[50];
	printf("Enter String:");
	scanf("%s",a);
	printf("String length=%d\n",strlen(a));
}

//输入一个数字，输出对应的星期的英文名称
#include <stdio.h>
char * week_day[8]={"sunday","monday","tuesday","wednesday","thursday","friday","saturday",NULL};
main(){
	int day;
	char *p,*lookstr();
	printf("Enter day:");
	scanf("%d",&day);
	p=lookstr(week_day,day);
	printf("%s\n",p);
}
char * lookstr(table,day)
	char *table[];
	int day;
	{
		int i;
		for(i=0;i<day&&table[i]!=NULL;i++);
			if(i==day&&table[i]!=NULL)
				return (table[day]);
			else return (NULL);
	}

//例5-14 输入3个数，输出最小者。
#include <stdio.h>
main(){
    int a,b,c,min;
    printf("Please input a,b,c\n");
    scanf("%d%d%d",&a,&b,&c);
    min=a<b?a:b;
    min=min<c?min:c;
    printf("min=%d\n",min);
}

//例 5-15 输入3个数，按从大到小的顺序输出
#include <stdio.h>
main(){
    int a,b,c,t;
    printf("Please input a,b,c\n");
    scanf("%d%d%d",&a,&b,&c);
    if(a<b){t=a;a=b;b=t;}
    if(a<c){t=a;a=c;c=t;}
    if(b<c){t=b;b=c;c=t;}
    printf("%d>=%d>=%d\n",a,b,c);
}

main(){
    int a,b,*pa,*pb;
    pa=&a,pb=&b;
    /*将从键盘输入的数据分别送到指针pa和pb指向的变量中*/
    scanf("%d%d",pa,pb);
    /*通过运算符实现间接访问*/
    printf("a=%d,b=%d\n",*pa,*pb);
}

#include <stdio.h>
main(){
    int a,b,c;
    printf("Enter A nd B ");
    scanf("%d%d",&a,&b);
    /*plus函数的实参为变量a和b的地址*/
    c=plus(&a,&b);
    printf("A+B=%d",c);
}
plus(px,py)
    /*形式参数px和py为指向整型的指针*/
    int *px,*py;
{
    return (*px+*py);
}

#include <stdio.h>
main(){
    int a,b,* pmax;
    /*说明函数max()的返回值为指向整型的指针*/
    int * max();
    printf("Enter a and b \n");
    scanf("%d%d",&a,&b);
    pmax=max(&a,&b);
    printf("max=%d\n",*pmax);
}
/*函数max的返回值为指向整型的指针*/
int * max(a,b)
    int *a,*b;
{
    int *p;
    p=*a>*b?a:b;
    return (p);
}