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昨晚我問了一個關於計算機科學課程的問題，其中我必須將中綴轉換爲後綴符號並進行評估。我能夠調試它並使其工作（有點），但是，我仍然爲某些表達式輸出奇怪的輸出。C++中綴到Postfix適用於某些輸入，但不適用於其他輸入？
它適用於像7 + 7,3 + 2等基本輸入的第一次迭代......但是，一旦你添加括號或其他表達式，它就會走出怪誕，我不知道爲什麼。
代碼如下，以及我正在獲取的文本文件/輸出。
頭文件
#ifndef STACK_H
#define STACK_H
/////////////////////////////////////////////////////
////Includes/////////////////////////////////////////
/////////////////////////////////////////////////////
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <stdlib.h>
#include <iomanip>
#include <sstream>
#include <stdio.h>
/////////////////////////////////////////////////////
using namespace std;
/*-------------------------------------------------------------------------------------------------------------*/
template <typename Object>
class Stack
{
private:
class stackListNode
{
public:
Object data;
stackListNode *next;
private:
//Nothing to declare-->placeholder since class
//sets data members to private initially
};
stackListNode *top;
public:
/////////////////////////////////////////////////
//Constructor Function//////////////////////////
Stack() {top = NULL;}
/////////////////////////////////////////////////
//Rest of functions defined inline for simplicity
void push(char token) // Push token onto the stack and create new node for top of stack
{
stackListNode *newNode = new stackListNode;
newNode->data = token;
newNode->next = top;
top = newNode;
}
char pop()
{
if(empty())
{
cout << "Stack is empty!\n" << endl;
return NULL;
}
stackListNode *temp = top;
top = temp->next;
return temp->data;
}
char peek()
{
if(empty())
{
cout << "Stack is empty!\n" << endl;
//exit(1);
return NULL;
}
return top->data;
}
int empty()
{
return top == NULL;
}
};
#endif
司機：
/////////////////////////////////////////////////////
////Includes/////////////////////////////////////////
/////////////////////////////////////////////////////
#include <iostream>
#include <fstream>
#include <string>
#include "Stack.h"
/////////////////////////////////////////////////////
using namespace std;
int precendence(char stack_beginning); //overloaded for character sitting at the front of the stack
void InFixToPostfix(ifstream& in_file);
//double EvaluatePostfix(double first_operand, double second_operand, char*myArray);
int main()
{
////VARS/////////////////////////////////////////////
string absolutePath;
cout << endl;
cout << "Please type in the name of the file you would to open \n";
cin >> absolutePath;
ifstream in_file;
in_file.open(absolutePath.c_str());
if(!in_file)
{
cout << "failed to open input file\n" ;
return 1 ;
}
else
{
InFixToPostfix(in_file); //kicks off program
}
}
void InFixToPostfix(ifstream& in_file)
{
string infix;
int right_parentheses = 0;
int left_parentheses = 0;
while(getline(in_file, infix))
{
char myArray[infix.length()];
strcpy(myArray, infix.c_str());
////////Declares a STRING Stack////////////////////////////////
Stack<char> stack_string;
////////Declares an Int Stack/////////////////////////////////
Stack<double> stack_int;
//////////////////////////////////////////////////////////////
int j = 0;
char *postfix = new char[infix.length()];
for(int i = 0; i < sizeof(myArray); i++)
{
int number = myArray[i] - '0';
if(number > 0)
{
postfix[j] = myArray[i];
j++;
//outputs the number b/c it is an operand
}
else if(myArray[i] == ')')
{
while(stack_string.peek() != '(')
{
cout << stack_string.peek() << " ";
stack_string.pop(); //pops to the peek
}
stack_string.pop(); // if there is a), pops to the peek
}
else if(myArray[i] == '+' || myArray[i] == '-' || myArray[i] == '/' || myArray[i] == '*' || myArray[i] == '(')
{
if(!stack_string.empty())
{
char stack_beginning = stack_string.peek();
int stack_top = precendence(stack_beginning);
//int stack_top = precendence(stack_string.peek());
int operatorHierarchy = precendence(myArray[i]);
//must be declared here because i will have been interated through array
while(operatorHierarchy >= stack_top)
{
stack_string.pop();
postfix[j] = myArray[i];
j++;
stack_top = precendence(stack_beginning);
operatorHierarchy = precendence(myArray[i]);
}
}
stack_string.push(myArray[i]);
}
}
while(!stack_string.empty())
{
char c = (char)stack_string.pop();
postfix[j] = c;
j++;
}
//////////Evaluate Section/////////////////////////////
cout << postfix <<endl;
for(int i = 0; i < j; i++)
{
//cout<<myArray[i]<<endl;
cout << postfix[i] <<endl;
int number = postfix[i] - '0';
if(number > 0) //this is a number
{
stack_int.push(number);
cout << stack_int.peek();
}
else if(postfix[i] == '*' || postfix[i] == '+' || postfix[i] == '-' || postfix[i] == '/')
{
double first_operand;
first_operand = stack_int.peek(); //fetches first operand on the stack_int
stack_int.pop();
//////////////////
double second_operand;
second_operand = stack_int.peek();
stack_int.pop();
//////////////////
if(postfix[i] == '+')
{
stack_int.push(second_operand + first_operand);
}
else if(postfix[i] == '-')
{
stack_int.push(second_operand - first_operand);
}
else if(postfix[i] == '*')
{
stack_int.push(second_operand * first_operand);
}
else if(postfix[i] == '/')
{
stack_int.push(second_operand/first_operand);
}
}
}
cout << (double)stack_int.pop() << endl;
}
}
int precendence(char stack_beginning)
{
int precendence;
if(stack_beginning == '(')
{
precendence = 3;
return precendence;
}
else if(stack_beginning == '*' || stack_beginning == '/')
{
precendence = 2;
return precendence;
}
//by making it 2, the precendence is dubbed less than +/-
else if(stack_beginning == '+' || stack_beginning == '-')
{
precendence = 1;
return precendence;
}
else
{
return 0;
}
} //by making it 1, the precendence is dubbed greater than */"/"
文本文件：
9+5
(4+2)
(3+8)/2
輸出：
Please type in the name of the file you would to open
f.txt
95+
9
5
+
14
+ 42
4
2
2
+ 382/
3
8
2
/
4