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C language

What is C:

C is a procedural programming language.
It was initially developed by Dennis Ritchie in 1972.
It was mainly developed as a system programming language to write UNIX OS.
It was developed to overcome the problems of previous languages such as B,BCPL etc.

Features of C:

Simple: This language provides structured approach to break the problem into parts.
Machine independent or portable: C program can be executed on different machines based on machine specific changes.
Structured programming language: We can break the program into parts using functions. functions also provide code reusability.
Memory Management: We can free the allocated memory at any time by calling the free() function.
Speed: The compilation and execution time of c language is fast.
Pointer: We can directly interact with the memory.
Recursion: We can call the function with in another function.

Structure of C program:

Header

Main()

Variable declaration

Body

Return Statement

Flow of execution:

Pre processor:

It is a tool that instructs the compiler to do pre processing before actual compilation.

All pre processor commands start with # symbol.

Ex: #include,#define.

Compiler:

Compiler is a translator that translates the source code from high level language to lower level language(assembly language,object code or machine code) to create executable code.

Assembler:

Compiler of assembly language.

Linker:

Linker is a program that combines one or more object file generated by compiler into single executable file,library file or another object file.

Loader:

A program which loads the executable file to primary memory of machine.

Pro's and Con's of C:

Pro's:

Building block for other languages.
Highly portable language.
Structured programming language.
Easy to learn.
Several built in functions in C library.
We can create user-defined functions to solve specific problem.
We can access hidden or blocked objects from use by other programming languages.
Speed up programs
Compile language
Easy to know how higher level languages works and interact with the machine.

Con's:

C does't have the concept of oops.
No run time checking.
No strict type checking.
Does't have the concept of namespace(Scope to the identifiers like functions,variables).
Does't have the concept of constructor and destructor.
Con't solve the real world programming tasks.
Extending the programming issues(errors and bugs)

Difference B/W Error,Defect,Bug,Fault and Failure:

A mistake in coding is called Error.
Error found by tester is called Defect.
Defect accepting by development team is called Bug.
If an end user finds an issue then that particular issue is Failure.
Fault is incorrect step or process or data definition.

Difference B/W Header file and Library:

Difference between Compiler and Interpreter

How to install C

There are many compilers to available to write C. Some of them are

Code Editors:

1) Turbo C/C++

2) GCC compiler

3)Net beans

4) VI/VIM Editor

5) Code Lite

6) Sublime Text

7) Blue fish

8) Microsoft visual studio
9) Code Block

Installing Turbo C++:

Step 1: Download Turbo C++

Step 2: Extract the downloaded zip file.

Step 3: Run the setup.exe file

Step 4: Complete the installation.

How to use Turbo C++:

1) First Start Turbo C++

2) select new file and write the c program

3) Press F2 for saving

4) Press Alt+F9 for compilation

5) Press Ctrl+F9 for run

Example:

Step 1: Write code in new file,save with .c extension.

Step 2: Compile the code. If there is an error rectify then run the code to get output.

Step 3: Press Alt F5 to see output.

Code:

Output:

Printf() and Scanf():

The printf() statement is used to print output in console.
Syntax: Printf("format string",argument list).
The format string can be %d-integer, %c-character, %s string, %f float.
The scanf() function is used to read the input from console.
Syntax: Scanf("format string",argument list).

Example:

Code:

Output:

Install and How to use GCC Compiler:

Step 1: Download Codeblocks-mingw-setup.exe file.

Step 2: Complete the installation.
Step 3: Copy the path in C drive up to bin folder and set environment variable.
Step 4: Write the code in Notepad++ or Edit Plus and save the file.
Step 5: Open Command prompt, goto directory where the file is saved.
Step 6: To compile file type the command gcc -o executableFileName fileName.c
Step 7: To run the file type fileName.exe or fileName

Code:

Output:

Real world applications of C:

Operating Systems
Development new languages
Computational platforms(MATLAB,Mathematica)
Embedded systems
Graphics and Games
Programming robots

Parts of C program:

Pre-processor
Header file
Function
Variables
Statements & expressions
Comments

Code:

Output:

C - Variable:

A variable is a named location in a memory to hold a value.
The value of C variable may get change in the program.
The variable might be belonging to any data type like int,float,char etc.
Memory space is not allocated at the time of variable declaration.
Memory space is allocated at the time of variable definition.
Variable initialization means assigning a value to the variable.

Declaring & Initializing a variable:

Types of Variable:
1) Local variable - The scope variable is with in the function only.
2) Global variable - The scope variable will be through out the program.
3) Environment variable - The scope variable will be available for all c applications and programs.The in-built functions which are used to access,modify and assign environment variables called environment functions{setenv(),getenv(),putenv()}.

Ex Code:

Output:

C - Data types:

Data types are used to define a variable before use in a program
Basic data types: int, char, float, double.
Enumeration data types: enum.
Derived data types: pointer,array,structure,union.
void data type: void.

Integer data type:

To store numeric values.
The storage size of int data type is 2 or 4 or 8 bytes depending upon the processor in cpu.
If we are using 16 bit processor 2 bytes(16 bits) {32 bit processor - 4 bytes, 64 bit processor - 8 bytes } of memory will be allocated to a variable.
We can't store decimal value in int data type.

Character data type:

The storage size of char is 1 byte.
We can store only one character in a variable.
To store more than one value we have to use array of characters concept.

Floating point data type:

Float data type is used to store decimal values.
Storage size of float is 4 bytes.
Ex: 9.238764 (contains 6 digits after decimal point)
Double data type is also same like float but it allows up to 10 digits after decimal point.

Enumerator data type :

Enumeration data type consists of named integer constants list.
Syntax: enum identifiers { enumerator-list }.

Ex Code:

Output:

Task: Declare string variable and assign your name and display your name

Code:

Output:

Task: Assign your name to 3 different variables Surname, First name, Last name and display your full name

Code:

Output:

Operators:

1) Arithmetic operators

2) Relational operators (>,<,<=,>=,==,!=)

3) Logical operators (&&,||,!)

4) Bitwise operators (&,|,`,^,>>,<<)

5) Assignment operators (=,+=,-=,*=,&,^)

6) Conditional operators (condition?true_value:false_value)

Ex Code:

Output:

Task: Display highest number in the above two numbers

Code:

Output:

Task on Logical operators:

Code:

Output:

Conditional Statements:

Decision control statements (if-else,nested if), group of statements are executed when condition is true

Syntax:

Case control statement (switch case) syntax:

Task: Ask the user to enter 3 numbers and display the largest number in that 3 numbers

Code:

Output:

Loop control statements

1) For

2) While

3) Do-while

4) Break - To exit from the loop

5) Continue - To continue the loop

Task: Ask the user to enter a number and display the multiplication table of that number

Code:

Output:

C - Function :

1) What is function?

C - function is a set of instructions to perform specific part in a program. Collection these functions creates a program.

2) Use of function:

Re-usability
Dividing big task into small pieces to achieve functionality.
Improve understandability of very large programs.
There is no limit to call a function.We can call any number of times.

3) Function declaration,Function call and Function definition:

Ex:

4) How to call function:
There are two ways to call a function in a program.Those are
i) Function by value - The value of variable is passed to the function as a parameter. Different memory will be allocated to both actual and formal parameters. Because, value of actual parameter is copied to formal parameter.
ii) Function by reference - The address of variable is passed to the function as a parameter.
Same memory will be allocated to both actual and formal parameters.

5) Types of function:
System defined - functions which are already defined in C library.
Ex: printf(), scanf(), strcat(), strcpy(), strlen().
User defined - functions which are defined by user.

Task: Write a function to add two numbers
Code:

Output:

Task: Write a function to display multiplication table
Code:

Output:

Input & Output functions:
The standard input - output header file (stdio.h) contains the definition of the functions which are used to display output on screen and to take input from user respectively.
Printf() - This function is used to display output. It will return number of characters printed by it.
Scanf() - This function is used to read an input from user. It will return number of characters read by it.
getchar() - This function reads a character and from the terminal and returns it as an integer.Reads single character at a time.
putchar() - This function displays a character passed to it on the screen and returns the same character. It displays only one character.
gets() - This function reads character entered from keyboard until new line is entered.
puts() - The string is displayed followed by new line character.
Note: Scanf() stops reading the characters when it encountered a space.Gets() read space as character too.

Ex:

Console I/O functions:
Keyboard and screen together called console.Console I/O functions classified into
1) Formatted Input/Output function - printf(),scanf(),sprintf(),sscanf().
sprintf() - writes to string.Instead of printing the output on the screen, it stores it in a character array.
sscanf() - reads from string.
2) Unformatted Input/Output function - getch(),getche(),getchar().

Ex:

Output:

File I/O functions:
Standard Files:
There are three file descriptor pointers predefined and opened.
stdin - standard input
stdout - standard output
stderr - standard error

fscanf() - It is like scanf() function, the given file descriptor pointer for the file to be read,the format string,address
Ex: fscanf(stdin,"%d",&m)
getc() - It is like getchar() to read character from opened file.
Ex: int getc(File *)
gets() - reads a string from standard output.
fgets() - It is to read a string from opened file.
fgetc() - reads a character from file.
fprintf() - It is for writing to a opened file in 'w' or 'a' mode.
Ex: fprintf(stdout,"%d",x)
putc() - for writing single character to standard output like putchar().
Ex: void putc(char ,File *); putc(ch,stdout);
puts() - It is like puts, puts(char *)
fputs() - It is to write a string to standard output. fputs(char *,file *).
fputc() - writes a character to file.
fread() - reads a block from a file.
fwrite() - writes a block to file.
fopen() - to open file stream.
fclose() - to close file stream.
fflush() - to clear the output stream buffer.

Mathematical functions:
The math.h header file supports all the mathematical related functions
floor() - returns the nearest integer which is less than or equal to the argument.
round() - returns rounded value.
ceil() - returns the nearest integer which is greater than or equal to the argument.
sqrt() - returns square root of argument value.
pow() - returns the power of number.
trunc() - This function truncates decimal value from floating number and returns an integer value.

Strings:

One dimensional array of characters terminated by a null character '\0'.

Syntax: char name[]="uma" (or) char name[4]={'u','m','a'};

Ex:

Output:

String Functions:

Code:

Output:

Pointers:

A pointer is a variable that holds address of another variable.
Direct address of the memory location.
These are used to allocate memory dynamically at execution time.
Always c pointer is initialized to null.The value of null is 0.
& symbol is used to get the address of variable.
* symbol is used to get the value of variable that is pointer is pointing to.
The size of any pointer is 2 byte for 16 bit compiler.

Pointer declaration:

type *var_name

Ex: int *p;

Code:

Output:

Recursion:

Recursion is the process of repeating items in self similar manner (or) process of iterating same task.

Code to find Factorial of Number:

Output:

Code to find Fibonacci series:

Output:

Arrays

An array is a data structure which is used to store a fixed size sequential collection of elements of the same type.

Syntax:

type arr_name[arr_size];

Task 1: Write a array to display our team names.

Code:

Output:

Files:

File is an object that stores data,information,settings or commands.
Why we need files because to handle the large quantity of data without any complexities.
Two types of files are existed.one is text file which contains information, another one is binary file which contains bytes or compiled version of text file.
File operations are

Creation of new file
Opening or accessing an existing file
Reading from a file
Writing to a file
Seeking in a file or moving to a specific location
Closing a file

The file pointer points to the structure that contains details of the file like name,size of the file,position,read/write status etc.
Syntax: FILE *fp
File modes for opening a file