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c programming session 1.pptx
1. UNIT II C PROGRAMMING BASICS
Problem formulation – Problem Solving - Introduction to ‘ C’
programming –fundamentals – structure of a ‘C’ program – compilation
and linking processes – Constants, Variables – Data Types – Expressions
using operators in ‘C’ – Managing Input and Output operations –
Decision Making and Branching – Looping statements – solving simple
scientific and statistical problems.
2. Problem formulation
• Effective problem formulation is fundamental to the success of all analysis,
but particularly in Command and Control assessment because the problems are
often ill-defined and complex, involving many dimensions and a rich context.
• Problem formulation involves decomposition of the analytic problem into
appropriate dimensions such as structures, functions, mission areas.
• Problem formulation is an iterative process that evolves over the course of
the study.
• It is essential even for small studies or where time is short; it will
save time later and help ensure quality.
3. • The problem formulation phase should identify the context of the
study and aspects of the problem related issues.
• There is no universally acceptable approach to problem
formulation. However, best practices exist that can be applied.
• First find out what the question is then find out what the real
question is.
4. PROBLEM SOLVING
•When we starts reading these and wants to learn how to solve problem by
using a computer, it is first of all important to understand what the problem
is.
•We need to read the problem statement a number of times to ensure that
it understands what is asked before attempting to solve the problem.
Method of Problem Solving
1. Recognize and understand the problem.
2. Accumulate facts.
3. Select appropriate theory.
4. Make necessary assumptions.
5. Solve the problem.
6. Verify results.
5. •Performing step 5 Solve the problem may involve a computer.
•The 5 steps in using a computer as a problem-solving tool
1. Develop an Algorithm and a Flowchart.
2. Write the program in a computer language.
3. Enter the program into the computer.
4. Test and' debug the program.
5. Run the program, input data, and get the results from the computer
6. Introduction to ‘ C’ programming
•C was developed by Dennis Ritchie at Bell laboratory in 1972
•It is an upgrade version of languages B and BCPL.
Features of C
•It is a structured programming language.
•It is highly portable.
•It is a middle level language.
•It is a case sensitive language.
•It uses Top-Down approach.
•It is a Free form language.etc,.
8. C Character Set
C Character Set
Execution
Character Set
Source
Character Set
Special
Characters
Digits
Alphabets Escape
Sequence
White
Spaces
9. C Character Set (Cont)
Source Character Set
It is used to construct the statements in the program.
Executable Character Set
These characters are employed at the time of execution i.e. they
have effects only when the program is being executed.
10. Source Character Set
Letters a to z ,A to Z
Digits 0 to 9
Special Characters ! @ # $ % ^ & * ( ) _ - + = | { } [ ]
etc,.
White Spaces Blank Space ,Horizontal tab, New
line, Vertical tab etc,.
11. Special characters
Comma ,
Period or dot .
Semicolon ;
Colon :
Apostrophe ‘
Quotation mark “
Exclamation mark !
Vertical bar |
Back Slash
Tilde ~
Underscore -
Dollar $
Question mark ?
12. Ampersand &
Caret ^
Asterisk *
Minus -
Addition +
Lesser than <
Greater than >
Parenthesis ()
Bracket []
Braces {}
Percentage %
Hash #
Equal to =
At the rate @
14. C Tokens
The smallest element in the C language is the token.
It may be a single character or a sequence of characters.
15. C Tokens (Cont)
C Tokens
Identifiers
Eg:main,
avg
Keywords
Eg: int,
for
operators
Eg: +
-
Strings
Eg: “ab”
spI
symbol
Eg: #
$ %
Constants
Eg:17,
15.5
16. Executing a C Program
Creating the Program
Compilation
Linking
Execution
17. Executing a C Program (Cont)
Enter the program in a C editor.
Save the program (File Save) or F2. Use the extension .c for
saving the file.
Eg: sample.c
Compile the program(Compile Compile) or Alt+F9.
Run the program(Run Run) or Ctrl+F9.
18. Executing C program using UNIX
Enter the program in vi editor.
Save the file using :wq
Use the extension .c for saving the file.
Eg: sample.c
Compile the program.
Eg: cc sample.c (or) gcc sample.c
Run the program using a.out.
19. Structure of C program
DOCUMENTATION SECTION
PREPROCESSOR SECTION
DEFINITION SECTION
GLOBAL DECLARATION SECTION
main()
{
Declaration part;
Executable Part;
}
sub program section
{
Body of the subprogram;
}
20. Documentation Section
It contains the comment lines.
Preprocessor Section
It is used to link library files.
Global Declaration Section
The Global declaration section comes at the beginning of the
program and they are visible to all parts of the program.
Declaration Section
It describes the data to be used within the function.
Executable Part
It contains the valid statements.
21. C Programs
C program may have many functions.
One and only one of the functions MUST BE named main.
main is the starting point for the program.
main and other functions in a program are divided into two
sections, declaration section and statement section.
22. Preprocessor Directives
Special instructions to the preprocessor that tells how to prepare the
program for compilation
E.g: include : tells the processor to include information from
selected libraries known as header files e.g. <stdio.h>
23. Comments (Program documentation)
The compiler simply ignores comments when it translates the
program into executable code.
To identify a comments, C uses opening /* and closing */
comment tokens.
24. Comments (Cont)
Comments can appear anywhere in a program.
Comments are also found wherever it is necessary to explain a point
about a code.
Comments cannot be nested in C i.e. you cannot have comments
inside comments.
25. C program
/* Example program in C*/ Comments
# include <stdio.h> Preprocessor Section
Global Declaration
void main ()
{ Local declaration
printf (“Hello World! n”); Statements
}
Output :
Hello World
27. Identifiers
Identifiers are names given to various program elements such as
variables, functions and arrays etc,.
Eg: #define N 10
#define a 15
Here N and a are user defined identifiers.
28. Rules for naming identifier
First character must be alphabetic or underscore.
Must consist only of alphabetic characters, digits, or underscores.
Only the first 31 characters of an identifier are significant and are
recognized by the compiler.
Cannot use a keywords or reserved word (e.g. main, include, printf &
scanf etc.).
No space are allowed between the identifiers etc,.
C is case sensitive, e.g. My_name my_name.
29. Examples of Valid and Invalid Names
Valid Names Invalid Names
a a1 $sum /* $ is illegal */
student_name stdntNm 2names /* Starts with 2 */
_aSystemName _anthrSysNm stdnt Nmbr /* no spaces */
TRUE FALSE int /* reserved word */
30. Variables
Variable is an identifier that is used to represent some specified type
of information.
Eg: x=3
Here x is variable.
32. Keywords
Auto register Continue
Double typedef For
Int Char signed
Struct extern void
Break return Default
Else union Goto
Long Const sizeof
Switch Float do
Case short If
Enum unsigned
Static While
33. Constants
It is an entity whose value does not changes during the execution.
Eg: x=3
Here 3 is a constant.
36. Numeric constants
Integer constants
It is formed using a sequence of digits.
Decimal - 0 to 9 .
Octal - 0 to 7.
Hexa - 0 to 9 ,A to F
Eg: 10,75 etc.
37. Rules for defining Integer Constant
It must have at least one digit.
Decimal point are not allowed.
No blank space or commas are allowed.
It can be either positive or negative. Etc,.
38. Numeric constants
Real constants
It is formed using a sequence of digits but it contain decimal point.
length, height, price distance measured in real number
Eg: 2.5, 5.11, etc.
39. Character constants
Single character constant
A character constant is a single character they also represented
with single digit or a single special symbol which is enclosed in
single quotes.
Eg: ‘a’, ‘8’,’_’etc.
41. Operators
An operator is a symbol that specifies an operation to be performed
on the operands.
Eg: a + b
+ is an operator.
a,b are operands.
42. Data Types
A Data type is the type of data that are going to access within the
program.
43. Standard Data Types
•These Standard type can be used to build more complex data types
called Derived Types (e.g. pointers, array, union etc.).
44. Data types
Data type Size(bytes) Range Format string
Char 1 -128 to 127 %c
int 2 -32,768 to 32,767 %d
Float 4 3.4 e-38 to 3.4 e+38 %f
Double 8 1.7 e-308 to 1.7 e+308 %lf
45. integer
A number without a fraction part : integral number.
C supports three different sizes of the integer data type :
short int
int
long int
46. Floating Point
A floating-point type is a number with a fractional part, e.g. 56.78
Floating point numbers are stored using
4 Byte.
Types
Float
Double
long double
47. character
Character are generally stored using 8 bits(1 Byte) of the internal
storage.
Character ASCII code value
a 97(decimal) or 01100001(binary)
x 120(decimal) or 01111000(binary)
48. void
The void type has no values and no operations.
Both the set of values and the set of operations are empty.
49. Variable’s Declaration
To create a variable, you must specify the type and then its
identifier :
float price;
int a,b;
char code;
50. Entire Data types in c:
Data type Size(bytes) Range Format string
Char 1 128 to 127 %c
Unsigned char 1 0 to 255 %c
Short or int 2 -32,768 to 32,767 %i or %d
Unsigned int 2 0 to 65535 %u
Long 4 -2147483648 to 2147483647 %ld
Unsigned long 4 0 to 4294967295 %lu
Float 4 3.4 e-38 to 3.4 e+38 %f or %g
Double 8 1.7 e-308 to 1.7 e+308 %lf
Long Double 10 3.4 e-4932 to 1.1 e+4932 %lf
52. Arithmetic operator
It is used to carry out arithmetic operations like addition,
subtraction etc,
Eg: + , - , * , / etc,
53. Sample program
#include<stdio.h> // Header File
#include <conio.h>
int b=10; //Global Declaration
void main ( ) /* main is the starting of every c program */
{
int a,c; //Local Declaration
clrscr( );
scanf(“%d”,&a);
printf(“ n The sum of the two values:”);
c = a+b;
printf(“%d”,c);
getch( );
}
54. Division operator on Different Data Type
Operation Result Example
int/int int 5/2 = 2
int/real real 5/2.0 = 2.5
real/int real 5.0/2 = 2.5
real/real real 5.0/2.0 = 2.5
57. Relational operator
It is used to compare two or more operands.
Eg :< , > , <= , >=, != etc,.
5 < 9 which will return 1
58. Logical operator
It is used to combine the result of two or more condition.
AND(&&)
OR (||)
NOT (!) are Logical operators.
Eg: (i>10)&&(j>5).
(i>10)||(j>5) etc,.
59. Sample program
#include<stdio.h>
#include <conio.h>
void main ( ){
int a=10,b=3,c=5,e;
clrscr( );
if(a>b) // relational operator
{
printf(" n a is bigger than b");
}
if((a>b)&&(a>c)) //Logical operator
{
printf(" n a is biggest");
}
getch( );
}
61. Assignment operator
It is used to assign a value or expression etc to a variable.
Eg: a =10.
a = b
a = b + c etc,.
62. Assignment operator(Cont)
Compound operator
It is also used to assign a value to a variable.
Eg: x + = y means x = x + y
Nested operator
It is used for multiple assignment.
Eg: i = j = k = 0;
65. Increment or decrement operator(Unary)
It is used to Increment or decrement an operand.
Eg: ++x (Pre Increment),
x++ (Post Increment),
--x (Pre Decrement),
x-- (Post Decrement).
66. Sample Program
#include<stdio.h>
#include <conio.h>
void main ( )
{
int a=5;
clrscr( );
printf(" n Post increment Value:%d",a++);
printf(" n Pre increment Value:%d",++a);
printf(" n Pre decrement Value:%d",--a);
printf(" n Post decrement Value:%d",a--);
getch( );
}
68. Bitwise operator
It is used to manipulate data at bit level.
Eg: a=5 i.e 0000 0101
b=4 i.e 0000 0100
Then a & b = 0000 0100
a | b = 0000 0101 etc,.
71. Conditional Operator (or) Ternary Operator
It is used to checks the condition and execute the statement
depending on the condition.
Eg: C = a > b ? a:b
77. Expression
An expression represent data item such as variable, constant are
interconnected using operators.
Eg:
Expression C Expression
a + b + c a + b + c
a2+b2 a*a + b*b
78. Operator Precedence & Associativity
The arithmetic expressions evaluation are carried out based on the
precedence and associativity.
The evaluation are carried in two phases.
First Phase: High Priority operators are
evaluated.
Second Phase: Low Priority operators are
evaluated.
85. Formatted Input/output
C uses two functions for formatted input and output.
Formatted input : reads formatted data from the keyboard.
Formatted output : writes formatted data to the monitor.
87. Standard Output
The standard output file is the monitor.
Like the keyboard, it is a text file.
When you need to display data that is not text, it must be
converted into to the text before it is written to the screen.
89. Formatted Input (scanf)
• The standard formatted input function in C is scanf (scan
formatted).
• scanf consists of :
a format string .
an address list that identifies where data are to be placed in
memory.
scanf ( format string, address list );
(“%c….%d…..%f…..”, &a,….&i,…..,&x…..)
96. Character Test Function
It is used to test the character taken from the input.
isalpha(ch)
isdigit(ch)
islower(ch)
isupper(ch)
tolower(ch)
toupper(ch) etc,.
97. Decision Making
It is used to change the order of the program based on condition.
Categories:
Sequential structure
Selection structure
Iteration structure
Encapsulation structure
98. Decision Making (cont)
Sequential structure
In which instructions are executed in sequence.
Selection structure
In which instruction are executed based on the result of some
condition.
Iteration structure
In which instruction are executed repeatedly.
Encapsulation structure
In which some compound structure are used.
99. SELECTION STRUCTURE
It allows the program to make a choice from alternative paths.
C provide the following selection structures
IF statement
IF … ELSE statement
Nested IF … ELSE statement
IF … ELSE ladder
104. #include<stdio.h>
#include <conio.h>
void main ( )
{
int a;
clrscr( );
printf("nEnter the number:");
scanf("%d",&a);
if(a>10)
{
printf(" n a is greater than 10");
}
else
{
printf(" n a is less than 10");
}
getch( );
}
139. switch(n)
{
case 1:
c=a+b;
printf("nThe result of Addition is:%d",c);
break;
case 2:
c=a-b;
printf("nThe result of Subtraction is:%d",c);
break;
case 3:
c=a*b;
printf("nThe result of Multiplication is:%d",c);
break;
case 0:
exit(0);
break;
}
getch();
}
140. Output
Enter the value of a,b:5
6
MENU
1.ADD
2.SUB
3.MULTIPLY
0.EXIT
Enter the choice:1
The result of Addition is:11
144. Sum of the Digits
#include<stdio.h>
#include<conio.h>
void main()
{
int r=0,sum=0,n;
printf("nEnter the no:");
scanf("%d",&n);
while(n>0)
{
r=n%10;
sum=sum+r;
n=n/10;
}
printf("sum of the digits is:%d",sum);
}
146. Reverse of a number
#include<stdio.h>
#include<conio.h>
void main()
{
int r=0,sum=0,n;
printf("nEnter the no:");
scanf("%d",&n);
while(n>0)
{
r=n%10;
sum=sum*10+r;
n=n/10;
}
printf("Reverse of the number is:%d",sum);
getch();
}
150. Swapping
#include<stdio.h>
#include <conio.h>
void main ( )
{
int a,b,c;
clrscr( );
printf(" nEnter the value of a:");
scanf("%d",&a);
printf(" nEnter the value of b:");
scanf("%d",&b);
c=a;
a=b;
b=c;
printf(" nThe value of a is:%d",a);
printf(" nThe value of b is:%d",b);
getch( );
}
151. Output:
Enter the value of a:5
Enter the value of b:4
The value of a is:4
The value of b is:5
152. Swapping without using third variable
#include<stdio.h>
#include <conio.h>
void main ( )
{
int a,b;
clrscr( );
printf(" nEnter the value of a:");
scanf("%d",&a);
printf(" nEnter the value of b:");
scanf("%d",&b);
a=a+b;
b=a-b;
a=a-b;
printf(" nThe value of a is:%d",a);
printf(" nThe value of b is:%d",b);
getch( );
}
153. Output:
Enter the value of a:5
Enter the value of b:6
The value of a is:6
The value of b is:5
