c programming language - iiitkalyani.files.wordpress.com · int struct break else long switch case...
TRANSCRIPT
TOPICS
C Introduction
C Flow Control
C Functions
C Programming Arrays
C Programming Pointers
C Programming Strings
Structure And Union
C Programming Files
Additional Topics
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FACTS ABOUT C
C was developed by Dennis M. Ritchie at Bell Labs.
C was invented to write an operating system called UNIX.
C is a successor of B language which was introduced around 1970
The UNIX OS was totally written in C by 1973.
The language was formalized in 1988 by the American National Standard Institute (ANSI).
Today C is the most widely used and popular System Programming Language.
Most of the state-of-the-art software's have been implemented using C.
Today's most popular Linux OS and RBDMS MySQL have been written in C. 3
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WHERE C USED AND WHY
C was adopted as a system development language because it produces code that runs nearly as fast as code written in assembly language.
Operating Systems
Language Compilers
Assemblers
Text Editors
Print Spoolers
Network Drivers
Modern Programs
Databases
Language Interpreters
Utilities 4
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FIRST PROGRAM
#include <stdio.h>
main ()
{
printf(“Hello World”);
}
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C INTRODUCTION
Keywords & Identifier
Variables & Constants
C Data Types
C Input/Output
C Operators
C Introduction Examples
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KEYWORDS
Keywords are the reserved words used in programming.
Each keywords has fixed meaning and that cannot be
changed by user.
For example:
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auto
double
int
struct
break
else
long
switch
case
enum
register
typedef
char
extern
return
union
continue
for
signed
void
do
if
static
while
default
goto
sizeof
volatile
const float
short
unsigned
IDENTIFIER
In C programming, identifiers are names given to C entities, such as variables, functions, structures etc. Identifier are created to give unique name to C entities to identify it during the execution of program. For
example:
int age;
void function() ;
Rules for writing identifier
1. An identifier can be composed of letters (both uppercase and lowercase letters), digits and underscore '_' only.
2. The first letter of identifier should be either a letter or an underscore. But, it is discouraged to start an identifier name with an underscore though it is legal. It is because, identifier that starts with underscore can conflict with system names. In such cases, compiler will complain about it. Some system names that start with underscore are _fileno, _iob, _wfopen etc.
3. There is no rule for the length of an identifier. However, the first 31 characters of an identifier are discriminated by the compiler. So, the first 31 letters of two identifiers in a program should be different.
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VARIABLES
Variables are memory location in computer's
memory to store data.
Rules for writing variable name in C
is same as writing identifier
Example:
int age;
int Student_name;
float salary;
char choice;
double number1, number2;
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CONSTANTS
Constants are the terms that can't be changed during the
execution of a program.
Integer constants
Decimal digits: 0 1 2 3 4 5 6 7 8 9
Octal digits: 0 1 2 3 4 5 6 7
Hexadecimal digits: 0 1 2 3 4 5 6 7 8 9 A B C D E F.
Notes:
1. You can use small caps a, b, c, d, e, f instead of uppercase
letters while writing a hexadecimal constant.
2. Every octal constant starts with 0 and hexadecimal
constant starts with 0x in C programming.
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CONT...
Floating-point constants
-2.0
0.0000234
-0.22E-5
Character constants
'a',
l',
'm',
'F' etc.
Enumeration constants
enum color {yellow, green, black, white}; 11
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DATA TYPE
Fundamental Data Types
Integer types
Floating Type
Character types
Derived Data Types
Arrays
Pointers
Structures
Enumeration
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DATA TYPE
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CONT...
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SAMPLE CODE
#include <stdio.h>
main ()
{
int sum=33;
float money=44.12;
char letter;
double pressure;
letter='E';
pressure=2.01e-10;
printf("value of sum is %d\n", sum);
printf("value of money is %f\n", money);
printf("value of letter is %c\n", letter);
printf("value of pressure is %e\n", pressure);
} 15
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OUTPUT OF SAMPLE CODE
value of sum is 33
value of money is 44.119999
value of letter is E
value of pressure is 2.010000e-10
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#DEFINE PREPROCESSOR
Names given to values that cannot be changed.
Implemented with the
#define preprocessor directive.
Example
#define N 3000
#define FALSE 0
#define PI 3.14159
#define FIGURE "triangle"
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THE #DEFINE PREPROCESSOR CONT...
#define identifier value
#include <stdio.h>
#define LENGTH 10
#define WIDTH 5
#define NEWLINE '\n'
int main()
{
int area;
area = LENGTH * WIDTH;
printf("value of area : %d", area);
printf("%c", NEWLINE);
return 0;
} 18
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REDEFINING PREPROCESSOR DIRECTIVE
ANYWHERE IN THE PROGRAM IS LEGAL
#include<stdio.h>
#define num 5
main()
{
#define num 100
printf(“%d”, num);
}
Output : 10 (with warning)
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THE CONST KEYWORD
const type variable = value;
#include <stdio.h>
int main()
{
const int LENGTH = 10;
const int WIDTH = 5;
int area; area = LENGTH * WIDTH; printf("value of
area : %d", area);
return 0;
} 20
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ENUMERATION
By default, value1 will be equal to 0, value2 will be 1
and so on but, the programmer can change the
default value.
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EXAMPLE OF EXTERN
First File: main.c
#include <stdio.h>
int count ;
extern void write_extern();
main()
{
count = 5;
write_extern();
}
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EXAMPLE OF EXTERN CONT..
Second File: support.c
#include <stdio.h>
extern int count;
void write_extern(void)
{
printf("count is %d\n", count);
}
Here, extern keyword is being used to declare count in the second file where as it has its definition in the first file, main.c. Now, compile these two files as follows:
$gcc main.c support.c
This will produce a.out executable program, when this program is executed, it produces the following result:
5
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INPUT / OUTPUT
ESCAPE SEQUENCE
1. \n Newline
2. \r Carriage return
3. \t Horizontal tab
4. \v Vertical tab
5. \\ \ character
6. \’ ' character
7. \“ " character
8. \? ? character
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JUST A LOOK
#include <stdio.h>
int main()
{
/* my first program in C */
printf("Hello, World! \n");
return 0;
}
A C program basically consists of the following parts:
Preprocessor Commands
Functions
Variables
Statements & Expressions
Comments
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HOW TO PRINT NUMBER
#include<stdio.h>
int main()
{
int c=5;
printf("Number=%d", c);
return 0;
}
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HOW TO TAKE INPUT FROM USER
#include<stdio.h>
int main()
{
int c;
printf("Enter a number\n");
scanf("%d",&c);
printf("Number=%d",c);
return 0;
}
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TEST YOUR KNOWLEDGE ? LAB EXEC 2
1. Write a program to print “Hello Friends”.
2. Write a program to accept two numbers from user
and display the result of [+, -, /, %, *].
3. Write a program to accept a two digit number and
find out reverse of that number.
4. WAP to find out the total income of husband and
wife by taking input in double.
5. WAP to take two number and swap then with the
help of third variable.
6. WAP to take two number and swap then without
the help of third variable.
7. WAP to accept a number and check for even and
odd.
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HOW TO ENTER CHARACTER
#include <stdio.h>
int main()
{
char var1;
printf("Enter character: ");
scanf("%c",&var1);
printf("You entered %c.",var1);
return 0;
}
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ASCII CODE
#include <stdio.h>
int main()
{
char var1;
printf("Enter character: ");
scanf("%c",&var1);
printf("You entered %c.\n",var1);
printf("ASCII value of %d",var1);
return 0;
}
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VARIATIONS IN OUTPUT FOR INTEGER AN FLOATS
#include<stdio.h>
int main()
{
printf("Case 1:%6d\n",9876);
/* Prints the number right justified within 6 columns */
printf("Case 2:%3d\n",9876);
/* Prints the number to be right justified to 3 columns but, there are 4 digits so number is not right justified */
printf("Case 3:%.2f\n",987.6543);
/* Prints the number rounded to two decimal places */
printf("Case 4:%.f\n",987.6543);
/* Prints the number rounded to 0 decimal place, i.e, rounded to integer */
printf("Case 5:%e\n",987.6543);
/* Prints the number in exponential notation(scientific notation) */
return 0;
}
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OUTPUT
Case 1: 9876
Case 2: 9876
Case 3: 987.65
Case 4: 988
Case 5: 9.876543e+002
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OPERATORS
Arithmetic Operators
Increment and Decrement Operators
Assignment Operators
Relational Operators
Logical Operators
Conditional Operators
Bitwise Operators
Special Operators
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ARITHMETIC OPERATORS
Operator Meaning of Operator
+ addition or unary plus
- subtraction or unary minus
* multiplication
/ division
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/* Program to demonstrate the working of arithmetic
operators in C. */
#include <stdio.h>
int 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);
return 0;
}
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INCREMENT AND DECREMENT OPERATORS
++ , --
(Prefix, Postfix)
{--a, ++a} {a--, a++}
Let a=5
a++; //a becomes 6
a--; //a becomes 5
++a; //a becomes 6
--a; //a becomes 5
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CONT....
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Prefix
int x =4, y;
y=++x;
printf(“x=%d,y=%d”,x,y);
Postfix
int x =4, y;
y=x++;
printf(“x=%d,y=%d”,x,y);
END
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