C programming:-

C is a genenral-purpose procedural-oriented programming language developed by Dennis M. Ritchie in year 1972.

C language is one of the most popular and most used compiled high-level programming language.
Dennis Ritchie Developed C in the Bell laboratory for creating system application that directly interacts with the hardware such as kernels, drivers etc.

Why learn C programming langugage?

Easy to learn
Structured language
Efficient programs
Low level memory management
Compiled in multiple platform

History of C programming language:

History of C is very interesting to know:

C programming language was developed by Dennis Ritchie at Bell laboratories of AT&T in USA.
It was developed to overcome the problem of the old lanugages as B, BPCL,etc.
Initially C was develop to be used in Unix operating system.

C inherits many feature of its predecessors languages such as B and BPCL.

Below is the table of some of the programming language developed before C

Languages	Year	Developed By
Algol	1960	International Group
BCPL	1967	Martin Richard
B	1970	Ken Thompson
Traditional C	1972	Dennis Ritchie
K & R C	1978	Kernighan & Dennis Ritchie
ANSI C	1989	ANSI Committee
ANSI/ISO C	1990	ISO Committee
C99	1999	Standardization Committee

Features of C programming :

There are 10 important features of C programming languages

Simple
Portable(Machine independent)
Mid-level programming lanugage
Structured programming lanugage
Rich library
Memory Management
Fast Speed
Pointers
Recursion
Extensible

1. Simple

C language is simple as it has easy to learn syntax, C programs can be structured(Can breaks into parts{function}),limited keywords.

2. Machine independent

Unlike Assembly language, C program can be run in different machines. with some specific changes in code, C program can be run in 32-bit and 64-bit or ARM-based machine.

3. Midlevel programming language

Although C language has many low-level programming features like Dynamic-memory-managment{Allocates memory in runtime(You'll be studying this in more detail later.)}, It supports feauters of high-level programming like arrays,structures,unions,etc

4. Structured programming language

C is a structured programming language in the sense that we can break the program into parts using functions. So, it is easy to understand and modify. Functions also provide code reusability.

5. Rich library

C language provides rich in-built functions that makes programming fast and effective.

6. Memory Management

It supports the feature of dynamic memory allocation. In C language, we can free the allocated memory at any time by calling the free() function.

7. Fast speed

The compilation and execution time of C language is fast since there are lesser inbuilt functions and hence the lesser overhead.

8. Pointers

C provides the feature of pointers. We can directly interact with the memory by using the pointers. We can use pointers for memory, structures, functions, array, etc.

9. Recursion

In C, we can call the function within the function. It provides code reusability for every function. Recursion enables us to use the approach of backtracking.

10. Extensible

C programs are extensible because we can implement new features in it.

Basic C program

    #include<stdio.h> //Header file
    /*Program starts with main()*/
    int main(){
        printf("Hello world"); //Prints value given in ()
    }

Explanation of the above program

#include<stdio.h> It is a header file that is needed to use the standard input-output library function. ex: printf(); function is defined in stdio.h.
int main();: It is the entry point of every program. Every C program will begin from main() function.
printf();: It print the data specified in between the () to the console.
return 0;: The return 0 statement, returns execution status to the OS. The 0 value is used for successful execution and 1 for unsuccessful execution.
```
Note : ";" *is used as a statement terminator. Every statement in C program ends with semicolon. Otherwise you will get a compile time error.* 
```

How to compile and run c programs?

Using an IDE
Using Commandline(Windows)/Terminal(linux or macos)

Using an IDE: You can either install an IDE which you can edit your C programs and run programs easily.

Below given some of the most used ide for C programming

DevC++
Codeblock
visual studio code (setting up vscode for C++ programs might be tricky)

Using Commandline(Windows)/Terminal(linux or macos)

        gcc file_name.c -o file_name_to_be_saved

example: you wrote a program and saved as file name "hello.c" and you want to execute the file. you can compile "hello.c" to any name you want. here we will make output file name as "greet"

       gcc hello.c -0 greet

Keywords in C

keywords	Description
auto	a default Storage class in C
else	a block of code execute when if condition fails
long	a datatype stores 8bytes ie. 2^(8-1) bit of integer range
switch	a conditional statement pairs with case
break	exits from the loops
enum	a user defined set of data types in c
register	a storage class in c that stores value in register
typedef	to define(name) a custom type
case	pairs with switch
float	a datatype to store floating-type numbers
short	a dattype to store small values
unsigned	to eliminate signed values
const	declares a constant value
for	defines a loop
signed	declares a signed value
void	void is a data type that returns nothing.
continue	skips a condition in a loop
goto	jumps to a specified location
sizeof	returns the size
volatile	data type?
default	paired with switch-case value
if	executes code if condition matches
static	preserve value in multiple runs
while	runs the code until the conditions fulfilled
do	paired with do-while
int	declares an integer of size 4 bytes
char	declares a character value of size 1 byte
struct	declares a structure datatype
double	declares a double data type of floating-point number with double precision of size 8 bytes
_Packed	used with union to elimiated padding in structure

Data types in C: -

There are following data types in C : -

Basic Data types: -
- Integer types
- Floating-point types
Enumerated types: - They are arithmetic types and used to define certain data types
Void type: - It is a type that has no value.
Derived data types: -
- Pointer
- Array
- Structure
- Union
- Function

Integer types: -

S.NO	Type	Storage Size	value range
1	char	1 byte	-128 to 127
2	unsigned char	1 byte	0 to 255
3	signed char	1 byte	-128 to 127
4	int	4 bytes	-2147483648 to 2147483647
5	unsigned int	4 bytes	0 to 65535
6	short	2 bytes	-32768 to 32767
7	unsigned short	2 bytes	0 to 65535
8	long	8 bytes	-9223372036854775808 to 9223372036854775807
9	unsigned long	8 bytes	0 to 18446744073709551615

References: -

Data Structure using c

deepaksy / C