// C++ program for different tree traversals
#include <iostream>

using namespace std;
 
/* A binary tree node has data, pointer to left child
and a pointer to right child */

struct Node {

    int data;

    struct Node *left, *right;

    Node(int data)

    {

        this->data = data;

        left = right = NULL;

    }
};
 
/* Given a binary tree, print its nodes according to the
"bottom-up" postorder traversal. */

void printPostorder(struct Node* node)
{

    if (node == NULL)

        return;
 

    // first recur on left subtree

    printPostorder(node->left);
 

    // then recur on right subtree

    printPostorder(node->right);
 

    // now deal with the node

    cout << node->data << " ";
}
 
/* Given a binary tree, print its nodes in inorder*/

void printInorder(struct Node* node)
{

    if (node == NULL)

        return;
 

    /* first recur on left child */

    printInorder(node->left);
 

    /* then print the data of node */

    cout << node->data << " ";
 

    /* now recur on right child */

    printInorder(node->right);
}
 
/* Given a binary tree, print its nodes in preorder*/

void printPreorder(struct Node* node)
{

    if (node == NULL)

        return;
 

    /* first print data of node */

    cout << node->data << " ";
 

    /* then recur on left sutree */

    printPreorder(node->left);
 

    /* now recur on right subtree */

    printPreorder(node->right);
}
 
/* Driver program to test above functions*/

int main()
{

    struct Node* root = new Node(1);

    root->left = new Node(2);

    root->right = new Node(3);

    root->left->left = new Node(4);

    root->left->right = new Node(5);
 

    cout << "\nPreorder traversal of binary tree is \n";

    printPreorder(root);
 

    cout << "\nInorder traversal of binary tree is \n";

    printInorder(root);
 

    cout << "\nPostorder traversal of binary tree is \n";

    printPostorder(root);
 

    return 0;
}

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Read inputs from stdin

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

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