C is ageneral-purpose, procedural programming languagedeveloped by Dennis Ritchie in 1972 at Bell Labs. It is known for its speed, efficiency, and close relationship to low-level hardware operations, making it widely used in system programming, operating systems (like UNIX), embedded systems, and software development.
Developed by: Dennis Ritchie
Year: 1972
Developed at: Bell Laboratories (USA)
Predecessor: B language (based on BCPL)
C influenced: C++, Java, C#, Objective-C, and many more
Simple and Easy to Learn
C has a small set of keywords and clean syntax, making it easy for beginners to understand and use.
Structured Language
C allows you to break programs into functions, making code more organized, readable, and easier to debug or modify.
Fast and Efficient
Programs written in C are close to hardware and execute very quickly, making C suitable for performance-critical applications.
Low-Level Access with Pointers
C supports pointers, which allow direct memory access—a powerful feature for system-level programming like OS or device drivers.
Portable Language
C programs can run on different machines with little or no modification, making it ideal for cross-platform development.
Rich Library
C provides a wide variety of built-in functions for tasks like input/output, memory management, and mathematical operations.
Modularity
C supports modular programming through functions, enabling better code reuse and maintenance.
Dynamic Memory Management
Through functions like malloc() and free(), C allows runtime memory allocation, which is essential for managing data efficiently.
Extensibility
New features or functions can be easily added to existing C programs without affecting the existing codebase.
Explanation:
#include <stdio.h>: Tells the compiler to include Standard Input Output library.
int main(): Every C program starts execution from main().
printf(): Used to print output.
return 0;: Exits the program successfully.
Reserved words that have specialmeaning to the compiler
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int – Integer type
float – Floating-point type
char – Character type
double – Double-precision float
void – No value/return type
if – Conditional statement
else – Alternative condition
switch – Multi-way branching
case – Used with switch
default – Default case in switch
for – Looping statement
while – Entry-controlled loop
do – Exit-controlled loop
break – Exit from loop or switch
continue – Skip to next loop iteration
goto – Jump to a label
return – Return from a function
auto – Default storage class
register – Store in CPU register
static – Preserve value between calls
extern – External global variable
signed – Signed data type
unsigned – Unsigned data type
short – Short integer
long – Long integer
const – Read-only variable
volatile – Variable may change unexpectedly
A comment is a code that is not executed by the compiler, and the programmer uses it to annotate their code, providing explanations or reminders about the code’s functionality, which aids in readability and future maintenance.
Data types in C define the type of data a variable can store. They tell the compiler how much memory to allocate and what kind of operations can be performed on that data.
| Data Type | Description | Example |
|---|---|---|
int | Stores integers | 10, -5 |
float | Stores decimal numbers | 3.14, -2.5 |
double | Stores large decimals | 2.56789 |
char | Stores a single character | ‘A’, ‘z’ |
void | No value (used in functions) | – |
These are based on primary types:
Array – Collection of similar data (e.g., int arr[10];)
Pointer – Stores address of another variable (e.g., int *ptr;)
Function – Returns a value (e.g., int add(int, int);)
Created by programmers:
struct – Group of variables (e.g., struct Student { int id; };)
union – Shares memory among members
enum – Defines named integer constants
typedef – Creates a new name for an existing type
Used to modify base types:
signed, unsigned, short, long
Escape sequences in C are combinations of characters that begin with a backslash (\) and are used to represent characters that cannot be typed directly. These sequences are interpreted in a special way when used inside string literals or character constants.
For example, the escape sequence \n represents a newline character, and \t represents a tab character. Here are some escape sequence characters used in C language.
\a produces a beep sound
\b adds a backspace
Newline Character
The carriage return, represented by the escape sequence \r in the C programming language, is a control character that resets the cursor position to the beginning of the current line. It doesn’t erase any characters but simply moves the cursor to the start of the line. The string “Hello” is printed first, then the carriage return moves the cursor back to the beginning of the line, and “World” is printed, overwriting “Hello.”
The null character is usually used to terminate a string
Conditional statements are used to perform operations based on some condition.
It allows a variable to be tested for equality against a list of values (cases).
Iterative statements facilitate programmers to execute any block of code lines repeatedly and can be controlled as per conditions added by the programmer.
It allows the execution of statements inside the block of the loop until the condition of the loop succeeds.
It is an exit-controlled loop. It is very similar to the while loop with one difference, i.e., the body of the do-while loop is executed at least once even if the expression is false
It is used to iterate the statements or a part of the program several times. It is frequently used to traverse the data structures like the array and linked list.
break keyword inside the loop is used to terminate the loop
Here is the output of the above code:
continue keyword skips the rest of the current iteration of the loop and returns to the starting point of the loop
