Arrays Notes

1. Input Operations,
Arrays, Declarations, Expressions,
Statements, Symbolic constant
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2. Revision
•It is possible to utilize an uppercase keyword as an identifier.
•Find out whether following are valid identifier. If not why?
◦ 12,245
◦ 36.0
◦ 10 20 30
◦ 123-45-6789
◦ 0900
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3. unsigned and long integer constants
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4. Average of Three Numbers
step 1: Get the input of three real numbers and store in n1,n2, n3
step 2: Calculate Total <- n1 + n2 + n3
step 3: Calculate average <- Total / 3
step 4: Print Total and average
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5. Simple Interest Calculation ??????????????
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6. Simple Interest Calculation
#include<stdio.h>
int main( )
{
int p, n ;
float r, si ;
p = 1000 ;
n = 3 ;
r = 8.5 ;
si = p * n * r / 100 ;
printf ( "%f" , si ) ;
}
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7. Input operations
• Input operations are used to read user input from the keyboard
• scanf() function is used to read multiple data values of different data types from the keyboard
Syntax:
scanf(“control string”, arg1, arg2, ………. argn);
 Control string (format string) specifies the field format
 Arguments arg1, arg2, …, argn specify the address of locations where
the data is stored
Inputting integer numbers:
%d
Percentage sign (%) indicates conversion specification, a data type character ( or type specifier)
Example:
scanf(“%d %d”, &number1, &number2);
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8. Input operations(cont…)
Inputting real numbers: %f
Example:
scanf(“%f %f”, &number1, &number2);
This statement will read the data: 50.35 23.0345
Inputting character strings: %s or %c
Example:
scanf(“ %s ”, name);
This statement will read the data: SASTRA
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9. Input operations(cont…)
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10. Home Work
1)Area of Rectangle
2)Area of Triangle
3)Farenheit to celcius conversion
4)Celcius to Farenheit conversion
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11. Array
An array is an identifier that refers to a collection of data items that all have the same name.
The data items must all be of the same type
The individual array elements are distinguished from one another by the value that is assigned
to a subscript.
Example
x is a 10-element array.
◦ The first element is referred to as x [ 0J ,the second as x [ 1J ,and so on.
◦ The last element will be x [9J .
If the array contains n elements, the subscript will be an integer quantity whose values range
from 0 to n-1 .
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12. Array (Cont….)
n-character string will require an (n+l )-element array, because of the null character (O) that is
automatically placed at the end of the string.
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13. Declarations
A declaration associates a group of variables with a specific data type.
All variables must be declared before they can appear in executable statements
It consists of a data type, followed by one or more variable names, ending with a semicolon
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14. Declarations (Cont…)
Initial values can be assigned to variables within a type declaration
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15. EXPRESSIONS
An expression represents a single data item, such as a number or a character.
It may consist of a single entity, such as a constant, a variable, an array element or a reference
to a function.
It may also consist of some combination of such entities, interconnected by one or more
operators.
It can also represent logical conditions that are either true or false
true and false are represented by the integer values 1 and 0, respectively.
 Examples are shown there
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16. STATEMENTS
A statement causes the computer to carry out some action.
Three different classes
◦ expression statements
◦ compound statements and
◦ control statements
Expression Statement
o consists of an expression followed by a semicolon.
o Several expression statements are shown below.
o a = 3;
o c = a + b ;
o ++i;
o p r i n t f ("Area = %f area) ;
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17. STATEMENTS(cont..)
Compound statement
◦ A compound statement consists of several individual statements enclosed within a pair of braces { }.
◦ a compound statement does not end with a semicolon
◦ A typical compound statement is shown below.
{
p i = 3.141593;
circumference = 2. * p i * radius;
area = p i * radius * radius;
}
Control Statement
Control statements are used to create special program features, such as logical tests, loops and branches.
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18. STATEMENTS(cont..)
Example
while (count <= n) {
p r i n t f ( ' x = ' ) ;
scanf ( "Skf" , &x) ;
sum += x;
++count;
}
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19. Symbolic Constants
A symbolic constant is a name that substitutes for a sequence of characters.
The characters may represent a numeric constant, a character constant or a string constant.
Thus, a symbolic constant allows a name to appear in place of those constant
When a program is compiled, each occurrence of a symbolic constant is replaced by its
corresponding character sequence.
It usually defined at the beginning of a program
typically written in uppercase letters
does not end with a semicolon
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20. Symbolic Constants(contd…)
Examples
#define TAXRATE 0.23
#define P I 3.141593
#define TRUE 1
#define FALSE 0
#define FRIEND "Susan“
Scenario 1
area = PI * radius * radius; statement will become area = 3.141593 * radius * radius;
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21. Symbolic Constants(contd…)
Scenario2
#define CONSTANT 6.023E23
……
….
p r i n t f ( "CONSTANT = %f “,CONSTANT) ;
......
...... p r i n t f statement would become p r i n t f ( "CONSTANT = %f 6.023E23) ; ,
during the compilation process.
Advantage
readily identified than the information that they represent
easier to change the value of a single symbolic constant than to change every
occurrence of some numerical constant that may appear in several places within the
program.
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