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+--- Thread: C++ script that involves classes, templates, and file handling (/Thread-C-script-that-involves-classes-templates-and-file-handling)
C++ script that involves classes, templates, and file handling - vluzzy - 01-02-2024
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
using namespace std;
// Templated Stack class
template <typename T>
class Stack {
private:
T* data;
int capacity;
int size;
public:
Stack(int capacity) : capacity(capacity), size(0) {
data = new T[capacity];
}
~Stack() {
delete[] data;
}
void push(T value) {
if (size < capacity) {
data[size++] = value;
} else {
cerr << "Stack overflow!" << endl;
}
}
T pop() {
if (size > 0) {
return data[--size];
} else {
cerr << "Stack underflow!" << endl;
return T(); // Return default value for simplicity
}
}
bool isEmpty() const {
return size == 0;
}
};
// Function to evaluate a postfix expression
template <typename T>
T evaluatePostfix(const string& expression) {
Stack<T> stack(20);
stringstream ss(expression);
string token;
while (ss >> token) {
if (isdigit(token[0])) {
stack.push(stod(token));
} else {
T operand2 = stack.pop();
T operand1 = stack.pop();
switch (token[0]) {
case '+':
stack.push(operand1 + operand2);
break;
case '-':
stack.push(operand1 - operand2);
break;
case '*':
stack.push(operand1 * operand2);
break;
case '/':
stack.push(operand1 / operand2);
break;
default:
cerr << "Invalid operator: " << token << endl;
break;
}
}
}
return stack.pop();
}
int main() {
ifstream inputFile("expressions.txt");
if (!inputFile.is_open()) {
cerr << "Failed to open the file." << endl;
return 1;
}
string line;
while (getline(inputFile, line)) {
cout << "Expression: " << line << endl;
double result = evaluatePostfix<double>(line);
cout << "Result: " << result << endl;
cout << "------------------------" << endl;
}
inputFile.close();
return 0;
}
Explanation:
The script defines a templated Stack class for managing a stack of values.
It implements a function to evaluate a postfix expression using the Stack class.
The main function reads expressions from a file (expressions.txt), evaluates them, and prints the results.