# include "stdio.h" 
# include "conio.h" 

void shi(); 
void cal(); 

main() 
{
  char c; 
  
  do 
  { 
    printf("========================================\n\n\n\n");
    printf(" 1. Calcullator\n"); 
    printf(" 2. Biao da shi\n"); 
    printf("\n\n\n\n========================================\n");
    printf("\n\n\n\nplease input you choice the number:\n");
    c=getchar(); 
    if(c=='1')cal(); 
    if(c=='2')shi(); 
    printf("please choice the number again\n"); 
  }
  while(c!='1'&&c!='2'); 
} 

void shi() 
{
  float a,b,c; 
  char ch ; 
  scanf("%f",&a); 
  do 
  {
    ch=getchar(); 
  }
  while(ch==' '); 
  
  scanf("%f",&b); 
  switch(ch) 
  {
  case '+':c=a+b;break; 
  case '-':c=a-b;break; 
  case '*':c=a*b;break; 
  case '/':c=a/b;break; 
  default:printf("error\n"); 
  } 
  printf("%f\n",c); 
  getch(); 
} 

void cal() 
{
  float a,b,c;
  char ch,key; 
  printf("iuput the frist value: "); 
  scanf("%f",&a); 
  printf("input symbol(+,-,*,/): "); 
  ch=getchar(); 
  while(ch!='+'&&ch!='-'&&ch!='*'&&ch!='/') 
  {
    if(ch!=' '&&ch!='\n')printf("please input right symbol (+,-,*,/):\n"); 
    ch=getchar(); 
  } 
  printf("iuput the second value: "); 
  scanf("%f",&b); 
  switch(ch) 
  {
  case '+':c=a+b;break; 
  case '-':c=a-b;break; 
  case '*':c=a*b;break; 
  case '/':c=a/b;break; 
  } 
  printf("\n\nthe result is : %f\n",c); 
  getch(); 
  do 
  { 
    printf("\n\n\nare you want to continu press c "); 
    printf("\nare you want to exit press x\n"); 
    for(key=getchar();key!='x'&&key!='c';) 
      key=getchar(); 
    
    if(key!='c') break; 
    clrscr(); 
    a=c;
    printf("the last result is : %f\n",a);
    printf("input symbol(+,-,*,/): ");
    do 
    { 
      ch=getchar(); 
    }
    while(ch==' '||ch=='\n'); 
    while(ch!='+'&&ch!='-'&&ch!='*'&&ch!='/') 
    {
      if(ch!=' ')printf("please input right symbol (+,-,*,/):\n"); 
      ch=getchar(); 
    } 
    printf("iuput the second value: "); 
    scanf("%f",&b); 
    switch(ch) 
    {
    case '+':c=a+b;break; 
    case '-':c=a-b;break; 
    case '*':c=a*b;break; 
    case '/':c=a/b;break; 
    } 
    printf("\n\nthe result is : %f\n",c); 
  }
  while(1); 
  
}