Download - INPUT/OUTPUT Statements
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INPUT/OUTPUT Statements
Dept. of Computer Engineering
Faculty of Engineering, Kasetsart University
Bangkok, Thailand
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Variable TypeData type
size description bound
bool 1 Byte To keep truth or false value.
true / false
char 1 Byte To keep one character acsii0 ถึ�ง ascii255
byte 1 Byte To keep positive number.
0 ถึ�ง 255
short 2 Bytes To keep short integer. -32,768 ถึ�ง 32,767
int 4 Bytes To keep integer. ประมาณ -2.1 x 106 ถึ�ง 2.1 x 106
long 8 Bytes To keep long integer. ประมาณ -9.2 x 1018 ถึ�ง 9.2 x 1018
float 16 Bytes
To keep real number.
double 32 Bytes
To keep real number. ประมาณ ± 5.0x10-324 ถึ�ง ± 1.7x10308
String Unlimit To keep several characters.
unlimit
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Special Character Special Character in C#
symbol result
\n Advance to a new line
\t Tab
\\ To type \
\' To type '
\" To type "
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Number Conversion To convert a numberic data type
<var> = (type) <var>example
byte boy; int imobile; long limit; double donut;
imobile = (int) boy ; limit = (long) boy + (long)imobile;donut = (double) imobile / 10;
boy = (byte)long + 3; imobile = (int)donut – 10;
C# will change numeric data type to the bigger one automatically.
error error
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Input Statement
คำ�าสั่��ง : Console.ReadLine( );– This command is used to read string from the keyboard.
Usually used with Parse.
Exampledouble num;string alpha;int unit;
num = double.Parse(Console.ReadLine());alpha = Console.ReadLine();unit = int.Parse(Console.ReadLine());
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Read Statement : Remark ReadLine() is used to read input from keyboard and assign to the
variable and curser start a new line.
The input value is always string.
ReadLine() usually uses with Parse() command : byte.Parse, short.Parse, int.Parse long.Parse, char.Parse, bool.Parse, float.Parse, double.Parse
ReadLine() is used to read a value to a single variable at a time. For example :
double num;
num = double.Parse(Console.ReadLine());
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Write Statement
Console.WriteLine(); This command is used to display the output on the screen. After the output is displayed, the curser is advanced to a new line.
Console.Write(); This command is used to display the output on the screen. After the output is displayed, the curser remains on the same line next to the last character. (The curser does not advance to a new line)
Example :
Console.WriteLine(“Hello World !!”);
Console.WriteLine(“What is your name? : ”);
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Write Statement : Syntax I
Write() / WriteLine() formats :
Console.Write( <string> );– Example 1 Console.Write("Hello world !!!\n "); – Example 2 Console.Write("204111");
Console.Write( <var> );– Example 1 Console.Write(num); – Example 2 Console.Write(sum);
Console.Write( <text> , <value0>,…,<valuen> );
– Value can be a variable or a constant and must be referenced in <text> by using the position order such as {0} means value at position 0.
– Example Console.Write("Hi, {0} ", st);
Fix text
Format items
List of value
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Write Statement : Syntax II
Variables in Console.Write() / Console.WriteLine() must be referenced by using its position symbol.
{0} means the 0th variable, {1} means the 1st variable and ….
Double quote must be used to enclose text and the position symbol of variable.
ExampleConsole.Write("X is {0}" , x);
Console.WriteLine("X+Y is {0}" , x+y);
Console.WriteLine("{0} + {1} = {2}",x,y,x+y);
Console.WriteLine(“Hello {0} how are you?”, stdName);
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Write Statement : Example
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Write Statement : Formatting Output
Syntax : {index [,alignment] [:formatString]}
The symbol {} is used to define starting and ending points of the text required to be formatted
index means the position of variables which start from 0, 1, 2,… respectively.
The same position can be referenced more than once.– Example: Console.WriteLine(“{0} - {0} = 0”,a);
alignment means printing justification. if position number , right alignment. If negative number, left alignment.
– Example: Console.WriteLine(“{0,-5} = {0,5}” , 10 , 5+5)
formatString is to define a format of text which is required to display on screen.
– Example: Console.WriteLine(“{0: dd mm yyyy}” , DateTime.Now);
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Write Statement : Formatting Output
Symbols which are used in Console.WriteLine() statement to
define output format.
Symbol meaning example result
D or d Decimal Console.WriteLine(“ {0:D} ",10}; 10
E or e Exponential Console.WriteLine(“ {0:E} ",10}; 1.000000E+001
F or f Fix Point Console.WriteLine(“ {0:F} ",10}; 10.00
X or x Hexadecimal Console.WriteLine(“ {0:X} ",10}; A
P or p Percent Console.WriteLine(“ {0:P} ",10}; 1,000.00 %
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Operators
symbol Number of variable meaning example
+ , - 1 Symbol the represent positive or negative number.
-5, -3, -a, +b
+, - 2 Addition and subtraction operators of 2 operands.
5+3 , a+10
* 2 Multiplication operator of two operands. 5*3, 10*0.1,
a*b , a+10*3
/ 2 Division operator of two operands 10/3 , 10.0/3,
b/a , a*b/3
% 2 Modulo operator of two operands. 10%3 , 7%5 , a%b
++(x) 1 Increment x by 1 (this operator must be done before other operators).
a=10; b = ++a; (=>b=11)
--(x) 1 Decrement x by 1 (this operator must be done before other operators).
a=10; b = --a; (=>b=9)
(x)++ 1 Increment x by 1 (this operator must be done after other operators).
a=10; b = a++; (=>b=10)
(x)-- 1 Decrement x by 1 (this operator must be done after other operators).
a=10; b = a--; (=>b=10)
= 2 Assignment sign a = 10+1
+ 2 String concatination (if + is used with string.) st = “Hello” + “World”
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Assignment Operator
Normally, = is used to assign the right side value to the left side variable but the statement can be coded in shorten format :
symbol Example result+= x += y x = x+ y
-= x -= y x = x- y
*= x *= y x = x* y
/= x /= y x = x/ y
%= x %= y x = x% y
++ x++ , ++x x = x+1
-- x-- , --x x = x-1
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Operator Priority
( )
++(x) , --(x), +(x), -(x)
* / %
+ -
= , += , -=, *=, /=, %=
(x)++ , (x)--
Highest precedence (perform first)
Lowest precedence (perform later)
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Thank you