#include<stdio.h>
int main()
{
float m,n,s;
float min(float a,float b);
printf("input m,n:");
scanf("%d,%d",&m,&n);
s=min(m,n);
printf("The min is:%d\n",s);
return 0;
}
float min(float a,float b)
{
float c;
if(a>b)
c=b;
else
c=a;
return c;
}

#include<stdio.h>
int main()
{
float m,n,s;
float max(float a,float b);
printf("input m,n:");
scanf("%d,%d",&m,&n);
s=max(m,n);
printf("The max is:%d\n",s);
return 0;
}
float max(float a,float b)
{
float c;
if(a>b)
c=b;
else
c=a;
return c;
}

#include<stdio.h>
int main()
{
float m,n,s;
float max(float a,float b);
printf("input m,n:");
scanf("%f,%f",&m,&n);
s=max(m,n);
printf("The max is:%f\n",s);
return 0;
}
float max(float a,float b)
{
float c;
if(a>b)
c=b;
else
c=a;
return c;
}

#include<stdio.h>
void main()
{
char c;
printf("请输入一个小写字母");
scanf("%c",&c);
while(1)
{
if('a'<=c&&'z'>=c)
{
printf("变换后为：%c\n",c-31);
return;
}
else
{
printf("请正确输入小写字母");
scanf("%c",&c);
}
}
}

#include<stdio.h>
main()
{char ch;
ch=getchar();
ch=ch-31;
putchar(ch);
}

#include<stdio.h>
#include<math.h>
void main()
{float x,y;
printf("please input a number x:\n");
scanf("%f",&x);
if(x>=-2&&x<=-1) y=sqrt(0.25-(x+1.5)*(x+1.5));
if(x>=-1&&x<0) y=-x-1;
if(x>=0&&x<=1) y=-x+1;
if(x>=1&&x<=2) y=-sqrt(0.25-(x-1.5)*(x-1.5));
printf("%.2f\n",y);
}

#include<stdio.h>
#include<math.h>
void main()
{int c,s; float w,p,f,d;
printf("please input s,w,p:\n");
scanf("%d%f%f",&s,w,p);
if (s>=3000)
c=12;
else
c=s/250;
switch(c)
{
case 0:d=0;break;
case 1:d=2;break;
case 2:
case 3:
case 4:d=5;break;
case 5:
case 6:
case 7:
case 8:
case 9:
case 10:
case 11:d=10;break;
case 12:d=15;break;
}
f=p*w*s*(1-d/100);
printf("%10.2f\n",f);
}

#include<stdio.h>
#include<conio.h>
#include<string.h>
int main()
{
char a1[20],a2[20],b[20];
int i,m,flag1,flag2;
int j=0;
char user[20]={"abc"};
char password[20]={"123"};
for(i=0;i<3;)
{
printf("user:");
gets(a1);
strlwr(a1);
for(m=0;m<20;m++)
{
if(a1[m]!=' ')
{
a2[j]=a1[m];
j++;
}
}
a2[j]='\0';
flag1=strcmp(user,a2);
if (flag1==0)
{
printf("password:");
while ((b[j++]=getch())!='\r')
printf("*");
b[j-1]='\0';
flag2=strcmp(password,b);
if(flag2==0)
{
printf("\n欢迎使用计算机！\n");
break;
}
else printf("\n密码错误\n");
}
else printf("用户名不存在\n");
if (i==2) printf("计算机已锁定，将无法使用！\n");
i++;
}
return 0;
}

#include<stdio.h>
#include<string.h>
void main()
{
int i,flag1,flag2;
char name[20]="lushan",password[10]="123456";
char person[20],password1[10];
for(i=0;i!=3;)
{
printf("Please input the name:\n");
gets(person);
flag1=strcmp(person,name);
printf("Please input the password:\n");
gets(password1);
flag2=strcmp(password,password1);
if(flag1==0&&flag2==0)
{
printf("Pass successfully!");
break;
}
else
{
printf("You have enter the wrong name or password!\n");
i++;
}
}
}

#include<stdio.h>
#include<string.h>
void main()
{
int i,flag1,flag2;
char name[20]="1",password[10]="2";
char person[20],password1[10];
for(i=0;i!=2;)
{
printf("Please input your id:\n");
gets(person);
flag1=strcmp(person,name);
printf("Please input your password:\n");
gets(password1);
flag2=strcmp(password,password1);
if(flag1==0&&flag2==0)
{
printf("Pass successfully!");
break;
}
else
{
printf("Account Suspended!\n");
i++;
}
}
}

#include <stdio.h>
#include <string.h>
void main()
{
int i=0;
while(i<3)
{
printf( "输入用户名：");
char name[10],psw[10];
scanf("%s",name);
printf("输入密码：");
scanf("%s",psw);
if((strcmp(name,"abc")==0)&&(strcmp(psw,"123456"))==0)
{
printf("welcome to use the software\n");
break;
}
i++;
}
if(i>=3)
{
printf("password error!you can not use software\n");
}
}

#include <stdio.h>;
#include <stdlib.h>;
main(){
int key,i;
printf("请输入密码：\n");
scanf("%d",&key);
if(key==123)
printf("welcome to use the software!\n");
else{
printf("请输入密码：");
scanf("%d",&key);
if(key==123)
printf("welcome to use the software!\n");
else{
printf("请输入密码：");
scanf("%d",&key);
if(key==123)
printf("welcome to use the software!\n");
else printf("password error!you can not use software!\n");
}
}
system("pause");
}

#include <stdio.h>;
#include <stdlib.h>;
main(){
int key,i,z;
printf("请输入id：\n");
scanf("%d",&i);
if(i==1)
{
printf("请输入密码：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else
printf("请输入密码：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else printf("password error!you can not use software!\n");
}
else
printf("请输入id：\n");
scanf("%d",&i);
if(i==1)
{
printf("请输入密码：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else printf("请输入密码：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else printf("password error!you can not use software!\n");
}
return 0;
}

#include <stdio.h>;
#include <stdlib.h>;
main(){
int key,i,z;
printf("please input your id：\n");
scanf("%d",&i);
if(i==1)
{
printf("please input your password：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else
printf("please input your password：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else printf("account suspended!\n");
}
else
printf("please input your id：\n");
scanf("%d",&i);
if(i==1)
{
printf("please input your password：：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else printf("please input your password：：\n");
scanf("%d",&z);
if(z==2)
printf("welcome to use the software!\n");
else printf("account suspended!\n");
}
return 0;
}