3.c

cx lka mgewra oi arwefjasl arew awejfiwerasekjgfna

#include <stdio.h> 
#include <conio.h> 
#include <stdlib.h> 
#include <process.h> 
#include <string.h> 
#define N 100 
double numStack[N]={0}; 
int numTop; 
char opStack[N]; 
int opTop; 

int op(char ch) 
{ 
if(ch=='+'||ch=='-') return 2; 
if(ch=='*'||ch=='/') return 3; 
if(ch=='(') return -1; 
return 0; 
} 

double result(double num1,char op,double num2) 
{ 
if(op=='+') return num1+num2; 
if(op=='-') return num1-num2; 
if(op=='*') return num1*num2; 
if(op=='/') return num1/num2; 
return 0; 
} 

int compute(char str[]) 
{ 
double num=0; 
int i=0,j=1,k=1; 
int Flag=0; 
numTop=opTop=0; 
while(str[i]!='\0'||opTop>0) 
{ 
if(str[i]>='0'&&str[i]<='9') 
if(Flag==0) 
num=num*10+str[i]-'0'; 
else 
{ 
num+=(str[i]-'0')/(j*10.0); 
j*=10; 
} 
else 
if(str[i]=='.') 
Flag=1; 
else 
if( k==1&&str[i]=='-'&&(i==0||op(str[i-1])) ) 
k=-1; 
else 
{ 
if(i>0&&!op(str[i-1])&&str[i]!='('&&str[i-1]!=')') 
{ 
numStack[numTop++]=num*k; 
num=0; j=1; Flag=0; k=1; 
} 
if(opTop==0||str[i]=='(') 
opStack[opTop++]=str[i]; 
else 
if(str[i]==')') 
{ 
while(opTop>0&&opStack[--opTop]!='(') 
{ 
numStack[numTop-2]=result(numStack[numTop-2],opStack[opTop],numStack[numTop-1]); 
numTop--; 
} 
if(opStack[opTop]!='(') return 0; 
} 
else 
{ 
if(str[i]=='\0'&&numTop==0) return 0; 
while(opTop>0&&op(str[i])<=op(opStack[opTop-1])) 
{ 
numStack[numTop-2]=result(numStack[numTop-2],opStack[--opTop],numStack[numTop-1]); 
numTop--; 
} 
if(str[i]!='\0') 
opStack[opTop++]=str[i]; 
} 
} 
if(str[i]!='\0') 
i++; 
} 
if(numTop!=1||opTop!=0) 
return 0; 
return 1; 
} 

void face() 
{ 
system("cls"); 
printf("__________________________________________________________________\n"); 
printf(" Save number(S) | Read number(R) | Clear(C) | Equal(E) | Quit(Q) \n"); 
printf("------------------------------------------------------------------\n"); 
} 

main() 
{ 
int i=0,j=0,k; 
char str[N]="\0"; 
char num[N]="\0"; 
char save[N]="\0"; 
char ch; 
double temp; 
unsigned long temp2; 
face(); 
printf("input an expression,press key 'E' to compute\n"); 
ch=getch(); 
while( 1 ) 
{ 
if(ch=='.'||ch==')'||op(ch)||ch>='0'&&ch<='9') 
{ 
str[i++]=ch; 
str[i]='\0'; 
face(); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",str); 
if( ch=='-'&&(i==1||op(str[i-2]))||ch>='0'&&ch<='9' ) 
{ 
num[j++]=ch; 
num[j]='\0'; 
} 
else j=0; 
} 
if(ch=='S'||ch=='s') 
if(strlen(num)) 
{ 
face(); 
printf("%s has been saved\n",strcpy(save,num)); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",str); 
} 
else 
{ 
face(); 
printf("there is no number to save!\n"); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",str); 
} 
if(ch=='R'||ch=='r') 
if(strlen(save)) 
{ 
face(); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",strcat(str,save)); 
i+=strlen(save); 
} 
if(ch=='C'||ch=='c') 
{ 
if(strlen(str)) 
str[--i]='\0'; 
face(); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",str); 
} 
if(ch=='E'||ch=='e') 
{ 
if(compute(str)) 
{ 
printf("\n=%g\n",numStack[0]); 
j=0; temp=numStack[0]; 
if(temp<0) 
{ 
temp=-temp; 
num[j++]='-'; 
num[j]='\0'; 
} 
temp2=(unsigned long)temp; 
k=1; 
while(temp2/k>=10) 
k*=10; 
while(k) 
{ 
num[j++]=temp2/k+'0'; 
num[j]='\0'; 
temp2=temp2%k; 
k/=10; 
} 
temp=temp-(int)temp; 
if(temp!=0) 
{ 
num[j++]='.'; 
num[j]='\0'; 
temp+=0.0000005; 
} 
for(k=6;k>0;k--) 
{ 
if(temp==0) break; 
temp*=10; 
num[j++]=(int)temp+'0'; 
num[j]='\0'; 
temp=temp-(int)temp; 
} 
} 
else 
{ 
face(); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",str); 
printf("\nwrong expression！"); 
} 
i=0; j=0; str[0]='\0'; 
} 
if(ch=='Q'||ch=='q') 
{ 
printf("\nare you sure to quit?（Y/N）\n"); 
ch=getch(); 
if(ch=='Y'||ch=='y') break; 
else 
{ 
face(); 
printf("input an expression,press key 'E' to compute\n"); 
printf("%s",str); 
} 
} 
ch=getch(); 
} 
}