CONDITIONAL STATETMENTS

2. Basics of Programming
Language – ‘C’

3.  Introduction to C Language
 C is a general-purpose, structured, procedural
programming language developed by Dennis Ritchie (1972)
at Bell Laboratories.
 It is widely used for system software, embedded systems,
operating systems, and compiler development due to its
efficiency, portability, and low-level memory access.

4.  Why Learn C Language?
 Forms the foundation of many modern languages like C+
+, Java.
 Helps understand memory management and hardware
interaction.
 Simple syntax and powerful features.

5.  Features of C Language
 Simple and efficient
 Structured programming
 Portable (machine independent)
 Rich set of operators
 Supports low-level programming
 Fast execution speed

6.  Applications of C Language
 Operating systems
 Embedded systems
 Compilers and interpreters
 Device drivers
 Database systems
 Scientific and engineering applications

7.  Getting Started with C
 C programs are written using a text editor, compiled using
a C compiler (e.g., GCC), and executed as machine code.
 C follows a structured programming approach, dividing
programs into functions for better modularity and
readability.

8.  The C Character Set
The C character set includes:
 Alphabets: A–Z, a–z
 Digits: 0–9
 Special Characters: + - * / % = < > ( ) { } [ ] ; , . _ #
 White Spaces: space, tab, newline

9.  Constants, Variables, and Keywords
 Constant: A fixed value that does not change during
program execution
 Variable: A named memory location whose value can
change
 Keyword: Reserved words with predefined meaning in C

10.  Types of C Constants
1. Integer Constants – e.g., 10, -25, 0
2. Real (Floating) Constants – e.g., 3.14, -0.005
3. Character Constants – e.g., 'A', '9', 'n'

11.  Rules for Constructing Integer Constants
 Must contain at least one digit
 No decimal point allowed
 Can be positive or negative
 No spaces or commas
 Examples: 25, -100, 0

12.  Rules for Constructing Real Constants
 Must contain a decimal point
 Can be positive or negative
 No spaces allowed
 Examples: 3.14, -0.25, 10.0

13.  Rules for Constructing Character Constants
 Enclosed in single quotes
 Contains only one character
 Examples: 'A', '5', 'n'

14.  Types of C Variables
Based on data types:
 int – integer variables
 float – decimal values
 double – high-precision decimals
 char – character data

15.  Rules for Constructing Variable Names
 Must start with an alphabet or underscore
 Can contain alphabets, digits, and underscore
 Cannot use keywords
 No special symbols or spaces
 Case-sensitive
Examples: total, _sum, count1

16.  C Keywords
 C has 32 reserved keywords, such as:
int, float, char, if, else, for, while, return, break, continue,
void
 Keywords cannot be used as variable names.

17.  Structure of a C Program
A C program is divided into different sections:
1. Documentation section
2. Link section
3. Definition section
4. Global declaration section
5. main() function
6. User-defined functions

20.  Input and Output in C
 Input and output are performed using standard functions.
 Commonly used functions:
• scanf() – for input
• printf() – for output

21.  Receiving Input
 C uses scanf() to take input from the user.
 scanf("%d", &x);
 & is the address operator
 Format specifiers define data type

22.  C Instructions
 C programs consist of instructions that perform actions.
Type Declaration Instruction
Used to declare variables before use.
 int a;
 float b;

23.  Arithmetic Instruction
Used to perform mathematical operations.
c = a + b * d;
Operators: + - * / %

24.  Hierarchy of Operations
Operator precedence in C:
1. * / %
2. + -
3. =
Parentheses override precedence.

25. [A] Point out the errors, if any, in the following C statements:
(a) int = 314.562 * 150 ;
(b) name = ‘Ajay’ ;
(c) varchar = ‘3’ ;
(d) 3.14 * r * r * h = vol_of_cyl ;
(e) k = ( a * b ) ( c + ( 2.5a + b ) ( d + e ) ;

26. [B] Evaluate the following expressions and show
their hierarchy.
(a) g = big / 2 + big * 4 / big - big + abc / 3 ; (abc = 2.5,
big = 2, assume g to be a float)

27. (b) on = ink * act / 2 + 3 / 2 * act + 2 + tig ; (ink = 4, act = 1,
tig = 3.2, assume on to be an int)

28. (c) s = qui * add / 4 - 6 / 2 + 2 / 3 * 6 / god ; (qui = 4,
add = 2, god = 2, assume s to be an int)

29.  What would be the output of the following programs:
(1) main( )
{
int i = 2, j = 3, k, l ;
float a, b ;
k = i / j * j ;
l = j / i * i ;
a = i / j * j ;
b = j / i * i ;
printf( "%d %d %f %f", k, l, a, b ) ; }

30. (2) main( )
{
float a = 5, b = 2 ;
int c ;
c = a % b ;
printf ( "%d", c ) ;
}