Postfix-Prefix to Infix

Author: RezaGooner

Postfix-Prefix to Infix/Postfix-Prefix to Infix.cpp

@@ -0,0 +1,127 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+const int MAX_SIZE = 100;
+
+struct Stack {
+    int top; // index of top of stack
+    string elements[MAX_SIZE];
+};
+
+bool isEmpty(Stack& stack) {
+    if (stack.top == -1) {
+        return true;
+    }
+    return false;
+}
+
+bool isFull(Stack& stack) {
+    if (stack.top == MAX_SIZE - 1) {
+        return true;
+    }
+    return false;
+}
+
+void push(Stack& stack, string value) {
+    if (isFull(stack)) {
+        //cout << "Stack overflow!" << endl;
+        return;
+    }
+    stack.elements[++stack.top] = value;
+}
+
+void pop(Stack& stack) {
+    if (isEmpty(stack)) {
+        //cout << "Stack underflow!" << endl;
+        return;
+    }
+    stack.elements[stack.top--] = "";
+}
+
+string top(Stack& stack) {
+    if (isEmpty(stack)) {
+        // cout << "Stack is empty!" << endl;
+        return "";
+    }
+    return stack.elements[stack.top];
+}
+
+bool isOperator(char c) {
+    return (c == '+' || c == '-' || c == '*' || c == '/');
+}
+
+string prefixToInfix(string prefixPhrase) {
+    Stack stack;
+    stack.top = -1;
+
+    int length = prefixPhrase.length();
+
+    for (int i = length - 1; i >= 0; i--) {
+        char currentChar = prefixPhrase[i];
+
+        if (isOperator(currentChar)) {
+            string operand1 = top(stack);
+            pop(stack);
+
+            string operand2 = top(stack);
+            pop(stack);
+
+            string newPhrase = "(" + operand1 + currentChar + operand2 + ")";
+            push(stack, newPhrase);
+        } else {
+            push(stack, string(1, currentChar));
+        }
+    }
+
+    return top(stack);
+}
+
+string postfixToInfix(string postfixPhrase) {
+    Stack stack;
+    stack.top = -1;
+
+    int length = postfixPhrase.length();
+
+    for (int i = 0; i < length; i++) {
+        char currentChar = postfixPhrase[i];
+
+        if (isOperator(currentChar)) {
+            string operand2 = top(stack);
+            pop(stack);
+
+            string operand1 = top(stack);
+            pop(stack);
+
+            string newPhrase = "(" + operand1 + currentChar + operand2 + ")";
+            push(stack, newPhrase);
+        } else {
+            push(stack, string(1, currentChar));
+        }
+    }
+    return top(stack);
+}
+
+int main() {
+    string prefixPhrase;
+    cout << "Enter prefix phrase, for example '+*AB-CD' : ";
+    cin >> prefixPhrase;
+    string infixPhrase = prefixToInfix(prefixPhrase);
+
+    cout << "Prefix to Infix Phrase: " << infixPhrase << endl;
+
+    string postfixPhrase;
+    cout << "Enter postfix phrase, for example'AB*CD-+' : ";
+    cin >> postfixPhrase;
+    infixPhrase = postfixToInfix(postfixPhrase);
+
+    cout << "Postfix to Infix Phrase: " << infixPhrase << endl;
+
+    return 0;
+}
+
+/*
+    Reza Asadi (Github : RezaGooner)
+	1402/08/25 ~ 2023/11/16
+*/