The document provides an overview of the C programming language, including its history, importance, and basic programming concepts such as algorithms, flowcharts, data types, constants, and variables. It explains the structure of algorithms and flowcharts with examples, and discusses the significance of C in terms of efficiency, portability, and speed. Additionally, it outlines key programming elements like keywords, identifiers, and the declaration of variables while highlighting the differences between constants and variables.

1. • Overview of C: History and importance C
• Algorithm :- ” A set of finite rules or instructions to be followed in
calculations or other problem-solving operations. ”
Therefore Algorithm refers to a sequence of finite steps to solve a
particular problem.
A set of steps that generates a finite sequence of elementary
computational operations leading to the solution of a given problem
is called an algorithm.
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2. Example of algorithm for addition of two number
Step 1. INPUT TO A, B
Step 2. S ← A+B --(Store the sum of the values in A and B in S)
Step 3. PRINT S --(Show the sum obtained in Step 2)
Step 4. STOP
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3. • Flowchart :- A flowchart is a blueprint that pictorially represents the algorithm and its steps.
• Formally speaking, a flowchart is a diagrammatic representation of the steps of an algorithm.
• In a flowchart, boxes of different shapes are used to denote different types of operations.
These boxes are then connected by lines with arrows denoting the flow or direction to which
one should proceed to know the next step.
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4. Example of flowchart
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5. C PROGRAMFOR ADDITIONOFTWO NUMBER
# include<stdio.h>
#include<math.h>
Int main ()
{
int a , b , c ;
a = 5;
b = 7;
c = a + b;
printf(“%d”, c )
return 0;
}
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6. • Overview of C: History and importance C
• Overview of C:
• It is a general-purpose, procedure-oriented programming language.
• It is both machine-independent and structured. C is a high-level programming language
developed by Dennis Ritchie in the early 1970s.
• It is now one of the most popular and influential programming languages worldwide.
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7. • History C
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8. • Importance of C :
UNIT –I Introduction to Program Planning & C Programming
•C allows for direct memory manipulation and low-level
access to system resources
Efficiency
•C code can be easily ported to different platforms & wide
availability of compilers and libraries.
Portability
•C is known for its fast execution speed, making it suitable
for developing performance-critical applications
Speed
•C gives programmers fine-grained control over memory
management and system resources
Control
•C code can be easily integrated with code written in other
languages like C++, Java, and Python
Compatibility
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9. • Character Set :
character set refers to a set of all the valid characters that we can use in the source program
for forming words, expressions, and numbers
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10. Tokens in C :
It is a smallest individual element of the C programming language that is meaningful to the compiler.
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11. • Keywords :
These are words that have special meaning to the C compiler.
UNIT –I Introduction to Program Planning & C Programming
auto break case char const
continue default do double else
enum extern float for goto
if int long register return
short signed sizeof static struct
switch typedef union unsigned void
volatile while
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12. • Identifiers :
These are unique names that are assigned to variables, structs,
functions, and other entities.
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Identifier Keyword
1 An identifier is a unique name created
by the programmer to define a
variable, structure, class, or function.
Keywords are restricted words with a definite,
predetermined meaning. Any programme
statement may be defined with the aid of
keywords.
2
A keyword always starts in lowercase.
The initial character in the identification can
be capitalized, lowercase, or start with an
underscore.
3 It can only have alphabetical
characters.
It can have numbers, alphabetical characters,
and underscores.
4 Examples of keywords are double, int,
auto, char, break, and many others.
Examples of IDs are test, count1, high speed,
etc.
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13. • Constants :
It is a value that remains constant throughout the program and
cannot be changed during program execution..
UNIT –I Introduction to Program Planning & C Programming
Constants
Primary
Integer
Real
Character
Secondary
Array
Pointer
Structure
Union
Enum , etc
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14. • Variables :
It is the name associated with some memory location to store data
of different types.
C Variable Syntax
Data type variable name = value;
or
data type variable_name1, variable_name2;
Example
Int var; // integer variable
char a; // character variable
float fff; // float variables
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15. UNIT –I Introduction to Program Planning & C Programming
• Data types :
• It specifies the type of data that the variable can store like integer, character, floating,
double, etc.
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16. UNIT –I Introduction to Program Planning & C Programming
• Declaration of variables:
• The main purpose of variable declaration is to store the required data in the memory
location in the form of variables so that we can use them in our program to perform any
operation or task.
• E xample:
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17. UNIT –I Introduction to Program Planning & C Programming
• Storage Classes in C
• C Storage Classes are used to describe the features of a variable/function.
• These features basically include the scope, visibility, and lifetime which help us to trace the existence
of a particular variable during the runtime of a program.
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18. UNIT –I Introduction to Program Planning & C Programming
• Assigning Values to variables:
 “Assigning a value to a variable” means writing a value to the variable.
This process involves four entities:
• A data type
• A variable
• The simple assignment operator (=)
• The value that will be copied to the variable.
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19. UNIT –I Introduction to Program Planning & C Programming
• Assigning Values to variables:
• Here:
• “ int ” is the data type.
• “ a ” is the variable.
• “ = " is the operator.
• “ 4 ” is the value.
“ int a = 4 ; ”
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20. UNIT –I Introduction to Program Planning & C Programming
• Defining Symbolic Constants:
• Labels/names that represent fixed values that never change during the course of a
program.
• Syntax for Creating Symbolic Constants
#define symbolic_constant_name value_of_the_constant
• Symbolic Constants Examples
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21. UNIT –I Introduction to Program Planning & C Programming
• declaring a Variable as Constant:
• To create a constant in C, use the const keyword followed by a data type and a variable
name.
• example:
const int MAX_VALUE = 100;
This will create a constant variable named MAX_VALUE with a value of 100.
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22. • Comparison between constants and variables :
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Constants Variables
1 A constant does not change its
value as the equation is solved.
A variable, on the other hand, changes
its value depending on the equation.
2 Constants are usually written in
numbers(whether fractions,
integers, decimals or real
numbers).
Variables are written as letters or
symbols.
3 Constants usually represent the
known values in an equation or
expression.
Variables, on the other hand,
represent unknown values.
4 Constants have fixed face
values.
Variables do not have a fixed face
value..
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23. Declaring a Variable as Volatile:
• When a variable is declared as volatile, it indicates to the compiler
that the variable’s value may change at any time without any
action being taken by the code the compiler finds nearby.
• The syntax for using the volatile keyword in C is as follows:
volatile data_type variable_name;
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24. Example of Declaring a Variable as Volatile:
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