//C Program for Inorder traversal of the binary search tree  
   
#include<stdio.h>  
#include<stdlib.h>  
  
struct node  
{  
    int key;  
    struct node *left;  
    struct node *right;  
};  
  
//return a new node with the given value  
struct node *getNode(int val)  
{  
    struct node *newNode;  
  
    newNode = malloc(sizeof(struct node));  
  
    newNode->key   = val;  
    newNode->left  = NULL;  
    newNode->right = NULL;  
  
    return newNode;  
}  
  
//inserts nodes in the binary search tree  
struct node *insertNode(struct node *root, int val)  
{  
     if(root == NULL)  
         return getNode(val);  
  
     if(root->key < val)  
         root->right = insertNode(root->right,val);  
  
     if(root->key > val)  
         root->left = insertNode(root->left,val);  
  
     return root;  
}  
  
//inorder traversal of the binary search tree  
void inorder(struct node *root)  
{  
    if(root == NULL)  
        return;  
  
    //traverse the left subtree  
    inorder(root->left);  
  
    //visit the root  
    printf("%d ",root->key);  
  
    //traverse the right subtree  
    inorder(root->right);  
}  
  
int main()  
{  
   struct node *root = NULL;  
  
  
    int data;  
    char ch;  
        /*  Do while loop to display various options to select from to decide the input  */  
        do      
        {  
            printf("\nSelect one of the operations::");  
            printf("\n1. To insert a new node in the Binary Tree");  
            printf("\n2. To display the nodes of the Binary Tree(via Inorder Traversal).\n");  
  
            int choice;  
            scanf("%d",&choice);              
            switch (choice)  
            {  
            case 1 :   
                printf("\nEnter the value to be inserted\n");  
                scanf("%d",&data);  
                root = insertNode(root,data);                    
                break;                            
            case 2 :   
                printf("\nInorder Traversal of the Binary Tree::\n");  
                inorder(root);  
                break;   
            default :   
                printf("Wrong Entry\n");  
                break;     
            }  
  
            printf("\nDo you want to continue (Type y or n)\n");  
            scanf(" %c",&ch);                          
        } while (ch == 'Y'|| ch == 'y');  
  
   return 0;  
}

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Read inputs from stdin

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

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

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);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

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.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

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
}