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Learning steps
Constants and Variable
Types of constants and Variables How to Identify Types
Rules for creating Variables
Keywords
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Learning Stepsy Learning C# language is similar to learning English
y It begin with Alphabets and digits.
yAlphabets to form words, words to form sentencesand sentences to form paragraph and the processcontinues
y Digits forms different numbers.
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The following help in building C# language
Alphabets, Digits and Special Symbols.
Constants & Variables Data Types.
Keywords
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Alphabets, Digits and Special
Symbolsy C# allows all alphabet irrespective of they are capital
letter i.e A-Z or small case letters .i.e a-z.
y Digit ranging from 0-9.y 32 special symbol in the keyboard.
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Constants&VariablesyAlphabets, digits and special symbols are combined to
form constants and variables.
y For example 3x+2y where 3and 2 are constants astheir values does not change ,they are also called asliterals.
y variables are x and y as their values changes ,they are
also called as identifiers.
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ConstantsThere are three types of Constants.
y Integer Constants
y Real Constantsy Character Constants
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Integer Constantsy Example of Integer constants are 23, 56, 678 etc.
Rules for creating Integer Constant
It should not have decimal point. It can be either +ve or-ve The default is +ve.
Within integer constant their should not be commaand space.
The valid range of integers constants is -2147483648 to+2147483647.
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RealConstantsy It must have decimal point present.
y It can be +ve or-ve. The default is +ve.
y There should not be a comma or space within realconstant.
yValid range of real constants is -3.4*1038 to +3.4*1038
y For example 427.62, -0.00254 can be expressed in the
form 4.2762E2,-2.54e-3 etc.
y The first form is fractional form and second form isknown as exponential form.
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Character ConstantsyWhen a character, digit or special symbol is written
within a pair of single inverted commas form a
character constant.y It can be capital letter, small case letter, a digit or
special symbol within single inverted commas.
y For example
y Zy Nagpur is not a character constant it is string
constants
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String Constantsy String constants are enclosed in double quotes
string message = Hello;
y for example Nagpur.
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Types ofConstants
11
Character constants char c = z
Numeric constants int a = 10;
Hexadecimal constants int hex = 0xFF;
Octal constants int oct = 011;
String constants char greetings = Hello;
Backslash constants \b, \f, \n, \r, \t, \, \, \0, \\,
\v, \a, \?, \OCTAL, \xHEX
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C# Data Types-PrimitivesData Types Ranges sizes
char 0 t0 65535 2
sbyte -128 to +127 1
short -32768 to +32767 2
int -2147483648 to+2147483647
4
long -9223372036854775808 to+92233720368547758087
8
float -3.4e38 to +3.4e38 4
double -1.7e308 to + 1.7e308 8
bool True/false 1
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VariablesyA name given to memory location whose value
changes is called as variable.
yNo of variables are equal to no of constants.
y for example
y x=3,y=4
y Z=x+y
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How to identify Typesy 3 Integer Constant
y 3.0 Real Constant
y 3 Character Constant
y int a float b char c
y a=3 b=3.0 c=3
y int ,float ,char data types /primitives
y a,b,c variables
y 3,3.0,3 constants/literals
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Rules for Building var. Namesy Cannot begin with a digit
y Rest can be alphabets,digits,underscores or $
y Ex pop98 , si_intyAny length.
y No commas or spaces.
yVariable names are case sensitives
y for example the following are consider differentvariables
y abc ABC Abc aBc AbC
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C# keywordsyWords whose meaning already stands explained to
machines are called as Keywords.
y77 keywords available in c#.
y int,float and char are keywords
y Reserved are same as keywords.
y Following declaration of variable will not work
y integer a
y real b
y character c
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y Proper declaration of variable which machineunderstands is
yint a
y float b
y char c