Input and output

Output to the screen

To send output to the screen the out command is used you'll already have seen this used in the preceding examples. If you want to display something on the screen followed by a line feed then use outl. Multiple strings and variables can be placed on the same line separated by a white space character.

//---------------------------------------

// File: ScreenOutput.e

//---------------------------------------

//---------------------------------------

// Block: go

//---------------------------------------

block Go

//assign different Variable types

BoolVar = true

ByteVar = 0xff

IntVar = 456

FloatVar = 0.565

StrVar = "test"

outl "Screen Output"

new_line

//display the Variables

out "Display byte: "

outl ByteVar

outl "Display bool: " BoolVar

outl "Display an int: " IntVar " then a float: " FloatVar

out "Display a string: "

outl StrVar

_block

In the above example You will also have noticed the command new_line has been used this adds a line feed.

There is a version of the out function that enables the printing of list variables (see 26) this command is coutlst it has two arguments the variable list to display and a delimiter string for example if you want to display a list variable separated by spaces then you would use

outlst Test ", "

If you want to print each element on a new line then use the constant #LF.

outlst Test #LF

The following shows this function in action.

//---------------------------------------

// File: OutList.e

//---------------------------------------

//---------------------------------------

// Block: Int

//---------------------------------------

block Int

I = 0

while I < 10

Test[I] = I

++ I

_while

//print list comma separated

outlst Test ", "

new_line

//print a list with line feeds

outlst Test #LF

new_line

_block

//---------------------------------------

// Block: Bool

//---------------------------------------

block Bool

Test[0] = false

Test[1] = true

//print list comma separated

outlst Test ", "

new_line

//print a list with line feeds

outlst Test #LF

new_line

_block

//---------------------------------------

// Block: Byte

//---------------------------------------

block Byte

Test[0] = 0x01

Test[1] = 0xff

//print list comma separated

outlst Test ", "

new_line

//print a list with line feeds

outlst Test #LF

new_line

_block

//---------------------------------------

// Block: Float

//---------------------------------------

block Float

Test[0] = 1.2

Test[1] = 1.3

Test[2] = 1.4

//print list comma separated

outlst Test " : "

new_line

//print a list with line feeds

outlst Test #LF

new_line

_block

//---------------------------------------

// Block: String

//---------------------------------------

block String

Test[0] = "abcde"

Test[1] = "efgh"

Test[2] = "ijkl"

//print list comma separated

outlst Test ""

new_line

//print a list with line feeds

outlst Test #LF

new_line

_block

//---------------------------------------

// Block: Go

//---------------------------------------

block Go

Int

Bool

Byte

Float

String

_block

Formatting Output

The information sent to the screen can be formated to allow for different alignment and number formats.

Alignment

The alignment of output can be set using the out_format command this allows specification of the width, a fill character and the type of alignment.

The alignment can be set to one of the following

#RIGHT This constant sets the text to be right justified at the specified width.

#LEFT This constant sets the text to be left justified.

#INTERNAL This constant pads out a numeric value to fill the field with spaces between the first character and any sign or base character.

The following code will produce the output

--10-right

…..........20-right

-xxxxxxx23

10-internal

- 244

20-internal

0-left

//---------------------------------------

// File: ScreenFormattedOutput.e

//---------------------------------------

//---------------------------------------

// Block: go

//---------------------------------------

block Go

out_format 10 '-' #RIGHT

outl "10-right"

out_format 20 '.' #RIGHT

outl "20-right"

out_format 10 'x' #INTERNAL

outl -23

outl "10-internal"

out_format 20 ' ' #INTERNAL

outl -244

outl "20-internal"

out_format 0 ' ' #LEFT

outl "0-left"

_block

Integer Data Formatting

When an integer or byte value is sent to the screen it can also be formatted with out_ibase format command.

The output can be set to one of the following.

#HEX any integer or byte variable will be displayed in a hexadecimal format.

#OCT any integer or byte variable will be displayed in octal format.

#DEC any integers or byte variable will displayed in decimal format.

Floating Point Formatting

The precision of decimal point output is set with the out_fprec command and the base can be set with the out_fbase command.

The precision sets the number of decimal places that are displayed.

The out_fbase command sets the base and format of the output

#DEFAULTFLOAT any float will be displayed in the default format.

#FIXED any float will be displayed in a fixed point format.

#SCIENTIFIC any float will be displayed in a scientific format using exponents.

#HEXFLOAT any float will be displayed in a hexadecimal format using exponents.

The following code demonstrates all the formatting options.

//---------------------------------------

// File: ScreenVariableFormat.e

//---------------------------------------

//---------------------------------------

// Block: NumberFormatCheck

//---------------------------------------

block FloatPrecisionCheck

Value1 = 1235.653

outl "Default: " Value1

out_fprec 1

outl "Precision 1: " Value1

out_fprec 2

outl "Precision 2: " Value1

out_fprec 7

outl "Precision 7: " Value1

_block

//---------------------------------------

// Block: FloatFormatCheck

//---------------------------------------

block FloatFormatCheck

Value1 = 1235.653

out_fbase #DEFAULTFLOAT

outl "DEFAULTFLOAT: " Value1

out_fbase #FIXED

outl "FIXED: " Value1

out_fbase #SCIENTIFIC

outl "SCIENTIFIC: " Value1

out_fbase #HEXFLOAT

outl "HEXFLOAT: " Value1

out_fbase #DEFAULTFLOAT

_block

//---------------------------------------

// Block: IntFormatCheck

//---------------------------------------

block IntFormatCheck

Value = 123456

out_ibase #DEC

outl "DEC: " Value

out_ibase #HEX

outl "HEX: " Value

out_ibase #OCT

outl "OCT: " Value

out_ibase #DEC

_block

//---------------------------------------

// Block: go

//---------------------------------------

block Go

FloatPrecisionCheck

new_line

FloatFormatCheck

new_line

IntFormatCheck

new_line

_block

Keyboard Input

There are three commands which allow input from the key board.

Reading Keyboard Input

The first command we will look at is the in command which allows text or numbers to be entered.

//---------------------------------------

// File: KeyBoardInput.e

//---------------------------------------

//---------------------------------------

// Block: go

//---------------------------------------

block Go

//Enter a string value

InputStrValue = "

out "Enter a string value: "

in InputStrValue

outl "You entered: " InputStrValue

new_line

//Enter a numeric value

InputNumericValue = 0

out "Enter a numeric value: "

in InputNumericValue

outl "You entered: " InputNumericValue

new_line

//Enter another value

out "Enter another value: "

in DefineValue

outl "You entered: " DefineValue

new_line

_block

The above code defines a string variable asks the user to input a string and then displays it.

It then repeats the process but with a numeric variable. If you try the code you will find that in this instance if you don't enter a numeric value then an error will be displayed and you will be asked to enter the value again.

In the last case the variable is not predefined so evolve creates it and assumes its a string.

Reading a Keyboard key

There are two command that can be used to get single characters from the key board they are key_in and key_inwait.

The difference is that the command key_in will read the keyboard and carry on while the key_inwait command will wait for a key to be pressed before continuing with the program.

Both commands will return the ASCII value of the button pressed if a numeric variable is passed into them or ASCII value if a string variable is passed into them. The variable is not predefined then a byte variable will be created and the value passed into this.

//---------------------------------------

// File: KeyInput.e

//---------------------------------------

//---------------------------------------

// Block: go

//---------------------------------------

block Go

//use a byte input

ByteInput = 0x00

//wait until a key is pressed

while ByteInput == 0

key_in ByteInput

_while

//display the key

outl "You typed :" ByteInput

//use a string input

StringInput = ""

while StringInput == ""

key_in StringInput

_while

//use a string input

outl "You typed :" StringInput

key_inwait ByteInput

//use a byte input

outl "You typed :" ByteInput

key_inwait StringInput

outl "You typed :" StringInput

_block