Complete C Programming Reference

C Programming Complete Notes

C Language — Developed by Dennis Ritchie in 1972 at Bell Laboratories. Often called the "mother of all programming languages."

01. C Language Basics

C is a general-purpose, procedural programming language that provides low-level memory access with a simple syntax. It forms the foundation of many modern languages including C++, Java, and Python.

Why C Matters? Every major operating system (Windows, Linux, macOS) has significant portions written in C. It gives you complete control over system resources.

Basic Structure of a C Program

#include <stdio.h>

int main() {
    printf("Hello, World!");
    return 0;
}

Program Explanation:

#include <stdio.h> - Header file for input/output functions
int main() - Main function where program execution begins
printf() - Function to display output
return 0; - Indicates successful program execution

02. C Keywords (32 Total)

Complete List of C Keywords

Keyword	Description
auto	Declares automatic (local) variable
break	Exits a loop or switch
case	Defines a block in switch-case
char	Character data type
const	Declares constant value
continue	Skips current iteration in loop
default	Defines default case in switch
do	Starts a do-while loop
double	Double-precision float
else	Alternate block in if-else
enum	Declares enumerated type
extern	Declares external variable or function
float	Floating-point variable
for	Starts a for loop
goto	Jumps to a label
if	Conditional branching
int	Declares integer variable
long	Declares long integer
register	Declares register variable
return	Returns from a function
short	Declares short integer
signed	Signed data type modifier
sizeof	Returns size of data type
static	Static storage class
struct	Declares structure
switch	Switch-case control
typedef	Defines new type name
union	Declares union
unsigned	Unsigned data type modifier
void	Declares empty return type
volatile	Tells compiler not to optimize
while	Starts a while loop

Note: All keywords are reserved words in C. You cannot use them as variable names or identifiers.

03. Data Types

Basic & Derived Data Types

Data Type	Description	Size (bytes)
int	Integer	4
char	Character	1
float	Floating point	4
double	Double-precision float	8
void	No value	-
short	Short integer	2
long	Long integer	4 or 8
signed	Signed type	-
unsigned	Unsigned type	-

// Example of different data types
int age = 25;
float price = 99.99;
char grade = 'A';
double pi = 3.14159265359;

04. Operators

C Operators Reference

Operator Type	Symbols
Arithmetic	+ - * / %
Relational	== != > < >= <=
Logical	&& \|\| !
Assignment	= += -= *= /= %=
Bitwise	& \| ^ ~ << >>
Increment/Decrement	++ --
Conditional	? :
Comma	,
Sizeof	sizeof()
Pointer	* &
Member Access	. ->

Arithmetic

Basic math operations: + - * / %

Relational

Comparisons: == != < > <= >=

Logical

Boolean logic: && (AND), || (OR), ! (NOT)

05. Escape Sequences

Escape Codes

Escape Code	Meaning
\n	Newline
\t	Tab
\\	Backslash (\)
\"	Double quote (")
\'	Single quote (')
\r	Carriage return
\b	Backspace
\f	Form feed
\a	Alert (beep)
\v	Vertical tab
\0	Null character

// Escape sequence example
printf("Hello\nWorld\tTabbed\n");
printf("Path: C:\\Program Files\\\n");
printf("She said, \"Hello!\"");

06. Special Symbols

Special Characters

Symbol	Purpose
;	Statement terminator
{ }	Block start and end
( )	Function and condition grouping
[ ]	Array subscript
#	Preprocessor directive
*	Pointer, multiplication
&	Address of operator
->	Access struct member via pointer
.	Access struct member

Pro Tips:

Always initialize variables before use
Use meaningful variable names
Comment your code for clarity
Check array bounds to avoid buffer overflow
Free dynamically allocated memory

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