unit 1 programming in c ztgdawte efhgfhj ewnfbshyufh fsfyshu

Computer systems
Computer hardware is the collection of physical
elements that comprise a computer system.
.
A computer system consists of
hardware and software.

Computer systems
.
Computer software is a collection of computer programs and related data that
provides the instructions for a computer what to do and how to do it. Software refers
to one or more computer programs and data held in the storage of the computer for
some purpose.

System Software
.
System Software: System software is responsible for managing a variety of
independent hardware components,so that they can work together.
• Device drivers
• Operating systems
• Servers
• Utilities
• Window systems
Programming Software: Programming Software usually provides tools to assist a
programmer in writing computer programs, and software using different
programming languages in a more convenient way.
• Compilers
• Debuggers
• Interpreters
• Linkers
• Text editors

Application Software
.
Application Software: Application software is developed to aid in any task that
benefits from computation. It is a broad category, and encompasses Software of
many kinds, including the internet browser being used to display this page. This
category includes:
• Business software
• Computer aided design
• Databases
• Decision making software
• Educational software
• Image editing

COMPUTER LANGUAGES
.
Application Software: Application software is developed to aid in any task that
benefits from computation. It is a broad category, and encompasses Software of
many kinds, including the internet browser being used to display this page. This
category includes:
• Business software
• Computer aided design
• Databases
• Decision making software
• Educational software
• Image editing

COMPUTER LANGUAGES
.
1. Low Level Languages.
2. High Level Languages.
Low Level Languages
Low level computer languages are machine codes or close to it. Computer cannot
understand instructions given in high level languages or in English. It can only
understand and execute instructions given in the form of machine language i.e.
language of 0 and 1. There are two types of low level languages:
Machine Language.
Assembly Language

COMPUTER LANGUAGES
.
Assembly Language
It was developed to overcome some of the many inconveniences of machine language.
This is another low level but a very important language in which operation codes and
operands are given in the form of alphanumeric symbols instead of 0‟s and l‟s. These
alphanumeric symbols will be known as mnemonic codes and can have maximum up to
5 letter combination e.g. ADD for addition, SUB for subtraction, START,LABEL etc.
Because of this feature it is also known as „Symbolic Programming Language‟. This
language is also very difficult and needs a lot of practice to master it because very
small.

COMPUTER LANGUAGES
.
High Level Languages
High level computer languages give formats close to English language and the purpose
of developing high level languages is to enable people to write programs easily and in
their own native language environment (English). High-level languages are basically
symbolic languages that use English words and/or mathematical symbols rather than
mnemonic codes. Each instruction in the high level language is translated into many
machine language instructions thus showing one-to-many translation.

Creating and Running Programs
.

There are four steps in this process.
1. Writing and editing the program using Text editor (source code).
2. Compile the program using any C compiler.(.bak file)
3. Linking the program with the required library modules(object file)
4. Executing the program. (.Exe file)
.

Creating and Editing a C Program in C Programming Language compiler:
Writing or creating and editing source program is a first step in c language. Source
code is written in c programming language according to the type of problem or
requirement, in any text editor.
Saving C Program in C Programming Language: Source code is saved on the
secondary storage. Source code is saved as text file. The extension of file must be
".c". Example the file name is "learn c programming languag
.

Compiling C program in C Programming Language: Computer does not understand c
programming language. It understands only 0 and 1 means machine language. So c
programming language code is converted into machine language.The process of
converting source code in to machine code is called compiling.Compiler is a program
that compiles source code. Compiler also detects errors in source program. If
compiling is successful source program is converted into object program. Object
program is saved on disk. The extension of file is ".obj"
Linking in C programming Language: There are many built in functions available in c
programming language. These functions are also called library functions. These
functions are stored in different header files.
.

Loading program: The process of transferring a program from secondary storage to
main memory for execution is called loading a program. A program called loader
does loading.
Executing program: Execution is the last step. In this step program starts execution.
Its instructions start working and output of the program display on the
screen.
.

C Program
1. #include <stdio.h>
2. #include <conio.h>
3. void main(){
4. printf("Hello C Language");
5. getch();
6. }
#include <stdio.h> includes the standard input output library functions. The printf()
function is defined in stdio.h .
.

C Program
#include <conio.h> includes the console input output library functions. The getch()
function is defined in conio.h file.
void main() The main() function is the entry point of every program in c language.
The void keyword specifies that it returns no value.
printf() The printf() function is used to print data on the console.
getch() The getch() function asks for a single character. Until you press any key, it
blocks the screen.
.

C TOKENS
The smallest individual units are known as tokens. C has six types of tokens.
1: Identifiers
2: Keywords
3: Constants
4: Strings
5: Special Symbols
6: Operators
.

Identifiers:
Identifiers refer to the names of variables, constants, functions and arrays. These are
user-defined names is called Identifiers. These identifier are defined against a set of
rules.
Rules for an Identifier
1. An Identifier can only have alphanumeric characters( a-z , A-Z , 0-9 ) and
underscore( _ ).
2. The first character of an identifier can only contain alphabet( a-z , A-Z ) or
underscore ( _ ).
3. Identifiers are also case sensitive in C. For example name and Name are two
different identifier in C.
4. Keywords are not allowed to be used as Identifiers.
.

Identifiers
5. No special characters, such as semicolon, period, whitespaces, slash or comma are
permitted to be used in or as Identifier.
6. C‟ compiler recognizes only the first 31 characters of an identifiers
Ex : Valid Invalid
STDNAME return
SUB $stay
TOT_MARKS 1RECORD
_TEMP STD NAME.
Y2K
.

Keywords
A keyword is a reserved word. All keywords have fixed meaning that means we
cannot change. Keywords serve as basic building blocks for program statements. All
keywords must be written in lowercase.
Example auto, break, case, char, const, continue, default etc.
Note: Keywords we cannot use it as a variable name, constant name etc.
.

Data Types/Types
To store data the program must reserve space which is done using datatype. A
datatype is a keyword/predefined instruction used for allocating memory for data. A
data type specifies the type of data that a variable can store such as integer, floating,
character etc. It used for declaring/defining variables or functions of different types
before to use in a program. There are 4 types of data types in C language.
.

Data Types/Types
Basic or Primary Data Type- int, char, float, double
Derived Data Type- array, pointer, structure, union
Enumeration Data -Type enum
Void Data Type- void
.
#include <stdio.h>
int main() {
int number1, number2, sum;
printf("Enter two integers: ");
scanf("%d %d", &number1,
&number2);
// calculate the sum
sum = number1 + number2;
printf("%d + %d = %d", number1,
number2, sum);
return 0;
}

Variables
A variable is a name of memory location. It is used to store data. Variables are
changeable, we can change value of a variable during execution of a program. . It can
be reused many times.
Note: Variable are nothing but identifiers.
Rules to write variable names:
1. A variable name contains maximum of 30 characters/ Variable
name must be upto 8 characters.
2. A variable name includes alphabets and numbers, but it must start
with an alphabet.
3. It cannot accept any special characters, blank spaces except under score( _ ).
.

Variables
4. It should not be a reserved word.
Ex : i ,rank1, MAX, min, Student_name.
StudentName , class_mark
Declaration of Variables : A variable can be used to store a value of any data type.
The declaration of variables must be done before they are used in the program. The
general format for declaring a variable.
Syntax : data_type variable-1,variable-2,------, variable-n;
Variables are separated by commas and declaration statement ends with a
semicolon. Ex : int x,y,z;
float a,b; char m,n;
.

Variables
Assigning values to variables : values can be assigned to variables using the
assignment
operator (=). The general format statement is :
Syntax : variable = constant;
Ex : x=100;
a= 12.25;
m=’f’;
char m=’f’;
.

Constants
Constants refer to fixed values that do not change during the execution of a program.
Note: constants are also called literals.
.

TYPES OF C CONSTANT
1. Integer constants
2. Real or Floating point constants
3. Character constants
4. String constants
5. Backslash character constants
.

TYPES OF C CONSTANT
Integer constants:
An integer constant is a numeric constant (associated with number) without any
fractional or exponential part. There are three types of integer constants in C
programming:
decimal constant(base 10)
octal constant(base 8)
hexadecimal constant(base 16)
For example:Decimal constants: 0, -9, 22 etc
Octal constants: 021, 077, 033 etc
Hexadecimal constants: 0x7f, 0x2a, 0x521 etc
.

TYPES OF C CONSTANT
Floating point/Real constants:
A floating point constant is a numeric constant that has either a fractional form or an
exponent form. For example: -2.0
0.0000234
-0.22E-5
.

TYPES OF C CONSTANT
Character Constant:
Single Character Constant : A character constant is either a single alphabet, a single
digit, a
single special symbol enclosed within single inverted commas.
a) it is value represent in „ „ (single quote).
b) The maximam length of a character constant can be 1 character.
EX : VALID INVALID
‘a’ “12”
.

Escape characters or backslash characters:
a) n newline
b) r carriage return
c) t tab
d) v vertical tab
e) b backspace
f) f form feed (page feed)
g) a alert (beep)
h) ‟ single quote(„)
i) ” double quote(“)
.
j) ? Question mark (?)
k) backslash ()

Two ways to define constant in C
.
1. const keyword
2. #define preprocessor
C const keyword
The const keyword is used to define constant in C programming.
const float PI=3.14;
Now, the value of PI variable can't be changed.
1. #include <stdio.h>
2. #include <conio.h>
3. void main(){
4. const float PI=3.14;
5. clrscr();
6. printf("The value of PI is: %f",PI);

.
7. getch();
8. }
Output:
The value of PI is: 3.140000
2) C #define preprocessor
The #define preprocessor is also used to define constant.
C#define
The #define preprocessor directive is used to define constant or micro substitution. It can use any
basic data type.

.
#include <stdio.h>
1. #define PI 3.14
2. main() {
3. printf("%f",PI);
4. }
Output:
3.140000

OPERATORS AND EXPRESSIONS:
.
Operators : An operator is a Symbol that performs an operation. An operators acts some variables are
called operands to get the desired result.Ex : a+b; Where a,b are operands and + is the operator.Types
of Operator :
1) Arithmetic Operators.
2) Relational Operators.
3) Logical Operators.
4) Assignment Operators.
5). Unary Operators.
6) Conditional Operators.
7) Special Operators.
8) Bitwise Operators.
9) Shift Operators.

Arithmetic Operators
.
An arithmetic operator performs mathematical operations such as addition, subtraction and
multiplication on numerical values (constants and variables).
#include <stdio.h>
void main()
{int a = 9,b = 4, c;
c = a+b;
printf("a+b = %d n",c);
c = a-b;
printf("a-b = %d n",c);
c = a*b;
printf("a*b = %d n",c);
c=a/b;
printf("a/b = %d n",c);
c=a%b;
printf("Remainder when a divided by b = %d n",c);
}

Relational Operators
.
A relational operator checks the relationship between two operands. If the relation is true, it returns 1; if the
relation is false, it returns value 0.

Relational Operators
Output
5 == 5 = 1
5 == 10 = 0
5 > 5 = 0
5 > 10 = 0
5 < 5 = 0
5 < 10 = 1
5 != 5 = 0
5 != 10 = 1
5 >= 5 = 1
5 >= 10 = 0
5 <= 5 = 1
5 <= 10 = 1
.
#include <stdio.h>
int main()
{int a = 5, b = 5, c = 10;
printf("%d == %d = %d n", a, b, a == b); // true
printf("%d == %d = %d n", a, c, a == c); // false
printf("%d > %d = %d n", a, b, a > b); //false
printf("%d > %d = %d n", a, c, a > c); //false
printf("%d < %d = %d n", a, b, a < b); //false
printf("%d < %d = %d n", a, c, a < c); //true
printf("%d != %d = %d n", a, b, a != b); //false
printf("%d != %d = %d n", a, c, a != c); //true
printf("%d >= %d = %d n", a, b, a >= b); //true
printf("%d >= %d = %d n", a, c, a >= c); //false
printf("%d <= %d = %d n", a, b, a <= b); //true
printf("%d <= %d = %d n", a, c, a <= c); //true
return 0; }

Logical Operators.
.
These operators are used to combine the results of two or more conditions. An
expression containing logical operator returns either 0 or 1 depending upon whether
expression results true or false. Logical operators are commonly used in decision making
in C programming

Logical Operators.
.
#include <stdio.h>
int main()
{
int a = 5, b = 5, c = 10, result;
result = (a = b) && (c > b);
printf("(a = b) && (c > b) equals to %d n", result);
result = (a = b) && (c < b);
printf("(a = b) && (c < b) equals to %d n", result);
result = (a = b) || (c < b);
printf("(a = b) || (c < b) equals to %d n", result);
result = (a != b) || (c < b);
printf("(a != b) || (c < b) equals to %d n", result);
result = !(a != b);
printf("!(a == b) equals to %d n", result);
result = !(a == b);
printf("!(a == b) equals to %d n", result);
return 0;
}
Output
(a = b) && (c > b) equals to 1
(a = b) && (c < b) equals to 0
(a = b) || (c < b) equals to 1
(a != b) || (c < b) equals to 0
!(a != b) equals to 1
!(a == b) equals to 0

Assignment Operators
.
Assignment operators are used to assign a value (or) an expression (or) a value of a variable to another
variable.
Syntax : variable name=expression (or) value (or) variable
Ex : x=10;
y=a+b;
z=p

Assignment Operators
.
#include <stdio.h>
int main()
{
int a = 5, c;
c = a;
C PROGRAMMING Page 37
printf("c = %d n", c);
c += a; // c = c+a
c -= a; // c = c-a
c *= a; // c = c*a
c /= a; // c = c/a
c %= a; // c = c%a
return 0;
}
Output
c = 5
c = 10
c = 5
c = 25
c = 5
c = 0

Increment and Decrement Operators /Unary Operators:
.
Unary operators are having higher priority than the other
operators. Unary operators, meaning they only operate
on a single operand.
#include <stdio.h>
int main()
{
int a = 10, b = 100;
float c = 10.5, d = 100.5;
printf("++a = %d n", ++a);
printf("--b = %d n", --b);
printf("++c = %f n", ++c);
printf("--d = %f n", --d);
return 0;
}
Output
++a = 11
--b = 99
++c = 11.500000
++d = 99.500000

Increment and Decrement Operators /Unary Operators:
.
#include<stdio.h>
void main() {
int i = 1;
printf("%d %d %d", i, ++i, i++);
}
Output : 3 3 1
#include<stdio.h>
#include<conio.h>
void main() {
int i = 0, j = 0;
j = i++ + ++i;
printf("%dn", i);
printf("%dn", j);
}
Output :
2
2

.
conditional operator checks the condition
and executes the statement depending of
the condition.
A conditional operator is a ternary
operator, that is, it works on 3 operands.
Conditional operator consist of two
symbols.
1 : question mark (?).
2 : colon ( : )
Syntax : condition ? exp1 : exp2;
#include <stdio.h>
int main(){
char February;
int days;
printf("If this year is leap year, enter 1. If not enter any integer: ");
scanf("%c",&February);
// If test condition (February == 'l') is true, days equal to 29.
// If test condition (February =='l') is false, days equal to 28.
days = (February == '1') ? 29 : 28;
printf("Number of days in February = %d",days);
return 0;
}
Output
If this year is leap year, enter 1. If not enter any integer: 1
Number of days in February = 29
Conditional Operator/ Ternary operator:

.
Bitwise operators are used to manipulate the data
at bit level. It operates on integers only. It
may not be applied to float.In arithmetic-logic unit
(which is within the CPU), mathematical
operations like: addition, subtraction, multiplication
and division are done in bit-level which
makes processing faster and saves power. To
perform bit-level operations in C programming,
bitwise operators are used.
Bitwise Operators:

.
Let us suppose the bitwise AND operation of two
integers 12 and 25.
12 = 00001100 (In Binary)
25 = 00011001 (In Binary)
Bit Operation of 12 and 25
00001100
& 00011001
________
00001000 = 8 (In decimal)
Bitwise AND operator &
Example #1: Bitwise AND
#include <stdio.h>
int main()
{
int a = 12, b = 25;
printf("Output = %d", a&b);
return 0;
}
Output
Output =8

.
The result of bitwise XOR operator is 1 if the
corresponding bits of two operands are opposite. It
is denoted by ^.
12 = 00001100 (In Binary)
25 = 00011001 (In Binary)
Bitwise XOR Operation of 12 and 25
00001100
| 00011001
________
00010101 = 21 (In decimal)
Bitwise OR operator |
#include <stdio.h>
int main()
{
int a = 12, b = 25;
printf("Output = %d", a^b);
return 0;
}
Output
Output = 21

.
The output of bitwise OR is 1 if at least one
corresponding bit of two operands is 1. In C
Programming, bitwise OR operator is denoted by |.
12 = 00001100 (In Binary)
25 = 00011001 (In Binary)
Bitwise OR Operation of 12 and 25
00001100
| 00011001
________
00011101 = 29 (In decimal)
Bitwise XOR (exclusive OR) operator ^
#include <stdio.h>
int main()
{
int a = 12, b = 25;
printf("Output = %d", a|b);
return 0;
}
Output
Output =29

.
Bitwise compliment operator is an unary operator
(works on only one operand). It changes 1 to 0
and 0 to 1. It is denoted by ~.
35 = 00100011 (In Binary)
Bitwise complement Operation of 35
~ 00100011
________
11011100 = 220 (In decimal)
2's Complement
Two's complement is an operation on binary
numbers. The 2's complement of a number is equal
to the complement of that number plus 1. For
example:
Bitwise complement operator ~

.
#include <stdio.h>
int main()
{
printf("complement = %dn",~35);
printf("complement = %dn",~-12);
return 0;
}
Output
Complement = -36
Complement = 11
Bitwise complement operator ~

.
There are two Bitwise shift operators in C
programming:
Right shift operator
Left shift operator.
Right Shift Operator
Right shift operator shifts all bits towards right by
certain number of specified bits. It is denoted
by >>.
Left Shift Operator
Left shift operator shifts all bits towards left by
certain number of specified bits. It is denoted by
<<.
Bitwise shift operators

.
1 ) Comma Operator :The comma operator is used
to separate the statement elements such as
variables, constants or expressions, and this
operator is used to link the related expressions
together, such expressions can be evaluated from
left to right and the value of right most
expressions is the value of combined expressions
Ex : val(a=3, b=9, c=77, a+c)
First signs the value 3 to a, then assigns 9 to b,
then assigns 77 to c, and finaly80(3+77) to
value.
Special Operators
2 ) Sizeof Operator : The sizeof() is a unary
operator, that returns the length in bytes o the
specified variable, and it is very useful to find the
bytes occupied by the specified variable in the
memory.
Syntax : sizeof(variable-name);
int a;
Ex : sizeof(a); //OUTPUT-----2bytes

.
#include <stdio.h>
int main()
{
int a, e[10];
float b;
double c;
char d;
printf("Size of int=%lu bytesn",sizeof(a));
printf("Size of float=%lu bytesn",sizeof(b));
printf("Size of double=%lu bytesn",sizeof(c));
printf("Size of char=%lu byten",sizeof(d));
printf("Size of integer type array having 10
elements = %lu bytesn", sizeof(e));
return 0;
}
Special Operators
Output
Size of int = 4 bytes
Size of float = 4 bytes
Size of double = 8 bytes
Size of char = 1 byte
Size of integer type array having 10 elements = 40
bytes

Operator Precedence and Associativity :

Operator Precedence : Arithmetic Operators are
evaluvated left to right using the
precedence of operator when the expression is
written without the paranthesis.They are two
levels of arithmetic operators in C.
1 : High Priority * / %
2 : Low Priority +
Ex : a=x-y/3+z*2+p/4.
x=7, y=9, z=11, p=8.
a= 7-9/3+11*2+8/4.
1 : a = 7-3+11*2+8/4
2 : a = 7-3+22+8/4
3 : a = 7-3+22+2:
1 : a = 4+22+2
2 : a = 26+2
3 : a = 28
Operator Precedence
9-12/(3+3)*(2-1)

Type Conversion
Sometimes, you have to convert the value of one data
type to another type. This is known as type conversion.
There are two types of conversion in C:
•Implicit Conversion (automatically)
•Explicit Conversion (manually)

// Automatic conversion: float to int
int myInt = 9.99;
printf("%d", myInt); // 9

int num1 = 5;
int num2 = 2;
float sum = (float) num1 / num2;
printf("%.1f", sum); // 2.5

unit 1 programming in c ztgdawte efhgfhj ewnfbshyufh fsfyshu

unit 1 programming in c ztgdawte efhgfhj ewnfbshyufh fsfyshu

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