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#include<iostream>
#include <stdio.h>
using namespace std;
struct Node
{
char data;
Node* next;
}*top=NULL;
void push(char x)
{
Node* t;
t = new Node;
if (t == NULL)
cout << "stack is full";
else
{
t->data = x;
t->next = top;
top = t;
}
}
char pop()
{
Node* t;
int x = -1;
if (top == NULL)
cout << "empty";
else
{
t = top;
top = top->next;
x = t->data;
delete t;
}
return x;
}
void Display()
{
Node* p;
p = top;
while (p)
{
cout << p->data<< " ";
p = p->next;
}
}
int isBalanced(char exp[])
{
int i;
for (i = 0; exp[i] != NULL; i++)
{
if (exp[i] == '(')
push(exp[i]);
else if (exp[i] == ')')
{
if (top == NULL)
return 0;
pop();
}
}
if (top == NULL)
return 1;
else
return 0;
}
int pre(char x)
{
if (x == '+' || x == '-')
return 1;
else if (x == '*' || x == '/')
return 2;
return 0;
}
int Operand(char x)
{
if (x == '+' || x == '-' || x == '*' || x == '/')
return 0;
else
return 1;
}
char* intopost(char infix[]) //후위연산자로 변환
{
char* postfix =NULL;
int len = strlen(infix);
postfix = new char[len + 2];
int i = 0, j = 0;
while (infix[i])
{
if (Operand(infix[i]))
postfix[j++] = infix[i++];
else
{
if (pre(infix[i]) > pre(top->data))
push(infix[i++]);
else
{
postfix[j++] = pop();
}
}
}
while (top != NULL)
postfix[j++] = pop();
postfix[j] = '\0';
return postfix;
}
int Eval(char postfix[])
{
int i = 0;
int x1, x2, r;
for (i = 0; postfix[i] != NULL; i++)
{
if (Operand(postfix[i]))
{
push(postfix[i]);
}
else
{
x2 = pop(); x1 - pop();
switch (postfix[i])
{
case '+':r = x1 + x2; break;
case '-':r = x1 - x2; break;
case '*':r = x1 * x2; break;
case '/':r = x1 / x2; break;
}
push(r);
}
}
return top->data;
}
int main()
{/*
char exp[] = "((a+b)*(c+d))";
cout << isBalanced(exp);*/
char infix[] = "a+b*c";
push('#');
//char *postfix= intopost(infix);
//cout << postfix;
char postfix[] = "234*+82/-";
Eval(postfix);
return 0;
}
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cs |
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