求ASCII码：
#include <stdio.h>
main()
{
char ch1,ch2,ch3;\\注意这里变量的取值是取字符型的
printf("input three numbers:");
ch1=getchar();
ch2=getchar();
ch3=getchar();
printf("\nASCII:%d %d %d\n",ch1,ch2,ch3);\\最后输入出的时候要打整数型...因为int就是十进制的，而ASCII也是十进制的，所以int = ASCII；
getch();
}
同学的个人信息：
#include <stdio.h>
void main()
{
long stu_id;\\长整型
char name[20];\\后面有[]的话，就是变成字符串了
char sex;\\字符型
char class_num[10];
char room_num[12];
char tel_num[12];
long qq_num[12];
long e_num[50];
printf("please input stu_id:\n");
scanf("%ld",&stu_id);
printf("please input name:\n");
scanf("%s",&name);
fflush(stdin);\\消除缓冲，
printf("please input sex(M/W):\n");
scanf("%c",&sex);
printf("please input class_num:\n");
scanf("%s",&class_num);
printf("please input room_num:\n");
scanf("%ld",&room_num);
printf("please input tel_num:\n");
scanf("%s",tel_num);
printf("please input qq_num:\n");
scanf("%ld",&qq_num);
printf("please input e_num:\n");
scanf("%s",&e_num);
printf("\n - - -%s data - - - - \n",name);
printf("==============================\n");
printf("stu_id\t\t%ld\n",stu_id);\\ \t是代表table的意思，就是间格
printf("name:\t\t%s\n",name);
printf("sex:\t\t%c\n",sex);
printf("class:\t\t%s\n",class_num);
printf("room:\t\t%s\n",room_num);
printf("tel_rum:\t%-s\n",tel_num);
printf("qq_num:\t\t%ld\n",qq_num);
printf("e_num:\t\t%s\n",e_num);
printf("===============================\n");
printf("Hello, world\n");
getch();
}
比较大小！
#include <stdio.h>
main()
{
int a,b=5;
printf("input one number0-9:");
scanf("%d",&a);
a<b?printf("this a num 5>%d",a):printf("this a num5<=%d",a);
\\三目运算： 条件 ？ 真 ： 假 “类似” if(条件){ 真 } else { 假 }
getch();
}
十进制转十六制：
#include <stdio.h>
main()
{
int n,n1,n2;
printf("please input a number <255 to n:\n");
scanf("%d",&n);
n1=n%16;
n2=n/16;
n1=n1>=10?'A'+n1-10 :'0'+n1;
n2=n2>=10?'A'+n2-10 :'0'+n2;
printf("%d的十六进制为:%c%cH",n,n2,n1);
getch();
}
