/*
Revesing a stack using recursion
    [0]             [4]
    [1]             [3]
    [2]     ====>   [2]
    [3]             [1]
    [4]             [0]
Author : github.com/Anirudhece
*/

#include <bits/stdc++.h>
using namespace std;

void insertAtBottom(stack<int>& st , int element){
    if(st.empty()){
        st.push(element);
    }
    else{
        int topElement= st.top();
        st.pop();
        insertAtBottom(st,element);
        st.push(topElement);
    }
}

void reverse(stack<int>& st){
    if(st.empty()){
        return;  // base condition
    }
    int element= st.top();
    st.pop();
    reverse(st);
    insertAtBottom(st,element);
}

int main()
{
    stack<int> stack1;
    stack<int> stack2;
    // push data into stack 1 (demoData-> 0 1 2 3)
    for (int i=0;i<4;i++) {  
        st.push(i);
    }

    stack2 = stack1;
    cout << "Original Stack" << endl;
    while (!stack2.empty()) {
        cout << stack2.top() << " ";
        stack2.pop();
    }
    cout<<endl;
    reverse(stack1);
    cout << "Reversed Stack" << endl;
    while (!stack1.empty()) {
        cout << stack1.top() << " ";
        stack1.pop();
    }
    return 0;
}
/*
Original Stack
3 2 1 0
Reversed Stack
0 1 2 3
*/

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}