我正在研究计算机科学课程。我把所有的东西都完成并分成了接口/实现，由于某种原因，程序无限循环并说“Stack is empty！”在调用peek（）函数之后。
我试过插入cout＆lt;＆lt;声明，看看我是否可以查明问题，但是，没有运气。如果其他人可以看一下，我将不胜感激。
谢谢
标题
#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;
}
int pop()
{
if(empty())
{
cout << "Stack is empty!\n" << endl;
return NULL;
}
stackListNode *temp = top;
top = temp->next;
}
char peek()
{
if(empty())
{
cout << "Stack is empty!\n" << endl;
return NULL;
}
return top->data;
}
int empty()
{
return top == NULL;
}
};
#endif
主档案：
/////////////////////////////////////////////////////
////Includes/////////////////////////////////////////
/////////////////////////////////////////////////////
#include <iostream>
#include <fstream>
#include <string>
#include "Stack.h"
/////////////////////////////////////////////////////
using namespace std;
int precendence(char stack_beginning); //ensures order of operations.
int precendence(char*myArray);
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.size()];
strcpy(myArray, infix.c_str());
for(int i = 0; i < sizeof(myArray); i++)
{
if(myArray[i] == '(')
{
right_parentheses++;
}
if(myArray[i] == ')')
{
left_parentheses++;
}
}
if(right_parentheses!=left_parentheses)
{
cout << endl;
cout << "There is a typo in one of the expressions in your file \n";
cout << "Please fix it and rerun the program \n";
exit(1);
}
for(int i = 0; i < sizeof(myArray); i++)
{
//int number = int(myArray[i]);
//deferences the pointer and reads each char in the array
//as an int rather than a character.
//int number = myArray[i];
if(isxdigit(myArray[i]) > 0) //function used to check for hexidecimal values (i.e. int's)
{
goto exit_out;
}
else if(myArray[i] == '(' || myArray[i] == ')' || myArray[i] == '+' || myArray[i] == '-' || myArray[i] == '*' || myArray[i] == '/' || myArray[i] == '\\' || myArray[i] == '\n')
{
goto exit_out;
}
else if(myArray[i] == char(32)) //checks to see if there is a space
{
goto exit_out;
}
else
{
cout << endl;
cout << "There is an invalid character in the file\n";
exit(1);
}
exit_out:;
}
////////Declares a STRING Stack////////////////////////////////
Stack<char> stack_string;
////////Declares an Int Stack/////////////////////////////////
Stack<int> stack_int;
//////////////////////////////////////////////////////////////
for(int i = 0; i < sizeof(myArray); i++)
{
int number = isxdigit(myArray[i]);
if(number > 0)
{
cout << number;
//outputs the number b/c it is an operand
}
if(myArray[i] == '(')
{
stack_string.push(myArray[i]);
}
if(myArray[i] == ')')
{
//cout << "test";
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
}
if(myArray[i] == '+' || myArray[i] == '-' || myArray[i] == '/' || myArray[i] == '*')
{
if(stack_string.empty())
{
stack_string.push(myArray[i]); //if there's nothing on the stack, pushes the current character
//goto done;
break; //breaks out of the statement
}
char stack_beginning = stack_string.peek();
int stack_top = precendence(stack_beginning);
//int stack_top = precendence(stack_string.peek());
int operatorHierarchy = precendence(myArray);
//must be declared here because i will have been interated through array
if(operatorHierarchy > stack_top)
{
stack_string.push(myArray[i]);
}
else if(operatorHierarchy <= stack_top) //could also be an if
{
dump_out:;
cout << stack_string.peek();
stack_string.pop();
int rerunThroughStack =0;
char new_stack_beginning = stack_string.peek();
rerunThroughStack = precendence(new_stack_beginning);
if(operatorHierarchy < stack_top)
{
stack_string.push(myArray[i]);
goto done; //could break
}
if(stack_string.peek() == '(')
{
stack_string.push(myArray[i]);
goto done;
}
if(stack_string.empty())
{
stack_string.push(myArray[i]);
goto done;
}
goto dump_out;
}
}
done:;
}
cout << stack_string.peek() << endl;
//////////Evaluate Section/////////////////////////////
for(int i = 0; i < sizeof(myArray); i++)
{
if(isxdigit(myArray[i]) > 0) //this is a number
{
stack_int.push(isxdigit(myArray[i]));
goto end;
}
else if(myArray[i] == '*' || myArray[i] == '+' || myArray[i] == '-' || myArray[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();
//////////////////
double answer;
answer = EvaluatePostfix(first_operand, second_operand, myArray); //THIS PROBABLY IS NOT RIGHT
stack_int.push(answer);
}
end:;
}
/*
int size_of_stack;
size_of_stack = stack_int.size();
if(size_of_stack == 1)
{
cout << stack_int.peek();
}
*/
}
}
double EvaluatePostfix(double first_operand, double second_operand, char* myArray) //might have to pass array as reference
{
/*
Cycle through the characters passed in through myArray[i];
*/
for(int i = 0; i < sizeof(myArray); i++)
{
if(myArray[i] == '*')
{
double first_answer;
first_answer = (second_operand * first_operand);
return first_answer;
}
else if(myArray[i] == '/')
{
double second_answer;
second_answer = (second_operand / first_operand);
return second_answer;
}
else if(myArray[i] == '+')
{
double third_answer;
third_answer = (second_operand + first_operand);
return third_answer;
}
else if(myArray[i] == '-')
{
double fourth_answer;
fourth_answer = (second_operand - first_operand);
return fourth_answer;
}
/*
else
{
cout << "There must be an error in your file" <<endl;
break;
exit(1);
}
*/
}
}
int precendence(char stack_beginning)
{
int precendence;
if(stack_beginning == '*' || stack_beginning == '/')
{
precendence = 2;
return precendence;
}
//by making it 2, the precendence is dubbed less than +/-
if(stack_beginning == '+' || stack_beginning == '-')
{
precendence = 1;
return precendence;
}
} //by making it 1, the precendence is dubbed greater than */"/"
int precendence(char*myArray)
{
int precendence;
for(int i = 0; i < sizeof(myArray); i++)
{
if(myArray[i] == '*' || myArray[i] == '/')
{
precendence = 2;
return precendence;
}
//by making it 2, the precendence is dubbed less than +/-
if(myArray[i] == '+' || myArray[i] == '-')
{
precendence = 1;
return precendence;
}
} //by making it 1, the precendence is dubbed greater than */"/"
}