#include <stdio.h>
#include <stdlib.h>
#define OK 2
#define TRUE 1
#define FALSE 0
#define ERROR -1
#define OVERFLOW -2
#define STACK_INIT_SIZE 100
#define STACKINCREMENT 10
typedef int status;
typedef struct{
int* base;
int* top;
int stacksize;
}SqStack;
status initStack(SqStack* S)
{
S->base=(int *)malloc(STACK_INIT_SIZE*sizeof(char));
if(!S->base)
exit(OVERFLOW);
S->top=S->base;
S->stacksize=STACK_INIT_SIZE;
return OK;
}
status push(SqStack* S,int e)
{
if(S->top-S->base >= S->stacksize)
{
S->base=(int*)realloc(S->base,(S->stacksize+STACKINCREMENT)*sizeof(int));
if(!S->base)
exit(OVERFLOW);
S->top=S->base+S->stacksize;
S->stacksize+=STACKINCREMENT;
}
*S->top++=e;
return OK;
}
status pop(SqStack* S,int* e)
{
if(S->base==S->top)
return ERROR;
*e=*--S->top;
return OK;
}
status stackEmpty(SqStack S)
{
if(S.base==S.top)
return TRUE;
else
return FALSE;
}
status getTop(SqStack S)
{
if(S.base!=S.top)
return *--S.top;
return ERROR;
}
status in(int c,int optrSet[7])
{
int i;
for(i=0;i<7;i++)
{
if(optrSet[i]==c)
{
return TRUE;
}
}
return FALSE;
}
char precede(int theta1,int theta2)
{
char priority;
if(theta1=='+' || theta1=='-')
{
switch(theta2)
{
case '+':
case '-':
case ')':
case '#':
priority='>';
break;
case '*':
case '/':
case '(':
priority='<';
break;
}
}
else if(theta1=='*' || theta1=='/')
{
switch(theta2)
{
case '+':
case '-':
case '*':
case '/':
case ')':
case '#':
priority='>';
break;
case '(':
priority='<';
break;
}
}
else if(theta1=='(')
{
switch(theta2)
{
case '+':
case '-':
case '*':
case '/':
case '(':
priority='<';
break;
case ')':
priority='=';
break;
case '#':
return ERROR;
}
}
else if(theta1==')')
{
switch(theta2)
{
case '+':
case '-':
case '*':
case '/':
case ')':
case '#':
priority='>';
break;
case '(':
return ERROR;
}
}
else if(theta1=='#')
{
switch(theta2)
{
case '+':
case '-':
case '*':
case '/':
case '(':
priority='<';
break;
case '#':
priority='=';
break;
case ')':
return ERROR;
}
}
else
{
return ERROR;
}
return priority;
}
int operate(int a,char theta,int b)
{
int result;
switch(theta)
{
case '+':
result=a+b;
break;
case '-':
result=a-b;
break;
case '*':
result=a*b;
break;
case '/':
result=a/b;
break;
}
return result;
}
int evaluateExpression()
{
SqStack opndSqStack;
SqStack optrSqStack;
int c,a,b,theta,x;
int optrSet[7]={'+','-','*','/','(',')','#'};
initStack(&opndSqStack);
initStack(&optrSqStack);
push(&optrSqStack,'#');
c=getchar();
while(c!='#' || getTop(optrSqStack)!='#')
{
if(!in(c,optrSet))
{
c-=48;
push(&opndSqStack,c);
c=getchar();
}
else
{
switch(precede(getTop(optrSqStack),c))
{
case '<':
push(&optrSqStack,c);
c=getchar();
break;
case '=':
pop(&optrSqStack,&x);
c=getchar();
break;
case '>':
pop(&optrSqStack,&theta);
pop(&opndSqStack,&b);
pop(&opndSqStack,&a);
push(&opndSqStack,operate(a,theta,b));
break;
}
}
}
return getTop(opndSqStack);
}
int main()
{
printf("result = %d",evaluateExpression());
return OK;
}
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