C Programming language

C Standard Library Function

Day 1: Introduction and brief history of C Programming language

Day 1: Advantages and Disadvantages of C, C Keywords, Data type modifiers in C

Day 1: Data types in C Programming language

Day 1: Secondary data types, Primitive and Non-primitive data types

Day 1: C Variables, C Constant, Format Specifiers in C

Day 2: Write first C program

Day 2: Flow of C program with example, main(), printf(), scanf()

Day 2: Operaters in C Programming language, Arithmetic operators

Day 2: Relational operators and Logical Operators in C Programming language

Day 2: Assignment, Increments and Decrement Operators in C Programming language

Day 3: Conditional statement: if else statement in C Programming language

Day 3: Conditional statement: switch statement in C Programming language

Day 3: Jump statements: return statement in C Programming language

Day 3: Jump statements: go to statement in C Programming language

Day 3: Jump statements: break statement in C Programming language

Day 3: Jump statements: continue statement in C Programming language

Day 4: Loops OR Iteration statement in C Programming language: for Loop

Day 4: Loops OR Iteration statement in C Programming language: while Loop

Day 4: Loops OR Iteration statement in C Programming language: do while Loop

Day 5: Array in C Programming language

Day 5: Access elements of Array in C Programming language

Day 5: One dimensional Array representation in memory using C Programming language

Day 5: Two dimensional Array representation in memory using C Programming language

Day 5: Multidimensional Array in C Programming language

Day 6: Function in C Programming language

Day 6: Definition, Declaration and Calling a Function in C Programming language

Day 6: Passing array to a function in C Programming language

Day 6: Calling Function in C Programming language : Call by value

Day 6: Calling Function in C Programming language : Call by reference

Day 6: Recursive Function in C Programming language

Day 6: Adding function to the library in C Programming language

Day 7: Pointer in C Programming language, How to use Pointer, Pointer declaration

Day 7: NULL Pointers in C Programming language

Day 7: Array of Pointers in C Programming language

Day 7: Pointer arithmetic in C Programming language

Day 7: Pointer to Pointer in C Programming language

Day 7: Pointer to Function in C Programming language: Passing pointers to functions

Day 7: Pointer to Function in C Programming language: Return pointer from functions

Day 8: Strings in C Programming language, Declaring String in C Programming language

Day 8: String functions in C Programming language

Introduction of Structure

Accessing the members of Structure

Structure With typedef Keyword and Use of sizeof function

Example of Structure

Dynamic memory allocation in C: Introduction

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Day 7 NULL Pointers in C Programming language
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# NULL Pointer

A pointer that is assigned NULL is called a null pointer. In that case no need to assigned to the exact address. This is done at the time of variable declaration. If a pointer contains the null (zero) value, it is assumed to point to nothing.

The NULL pointer is a constant with a value of zero defined in several standard libraries. Consider the following program:

#include <stdio.h>

void main ()
{
   int  *ptr = NULL;

   printf("The value of ptr is : %x\n", ptr  );
}
Output

The value of ptr is 0

Note: On most of the operating systems, programs are not permitted to access memory at address 0 because that memory is reserved by the operating system.

To check for a null pointer you can use an if statement as follows:

if(ptr)     /* succeeds if p is not null */
if(!ptr)    /* succeeds if p is null */
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