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I/O Statements

DISPLAY

The DISPLAY statement outputs the values passed to the output stream. CRLF means line break and is a sugar syntax for the "\n" escape sequence.

Syntax:

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DISPLAY <multiple NUMBER, TEXT, TEXT-VAR, NUMBER-VAR or CRLF>

Example:

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DISPLAY "Hello, " nameVariable "! This is a number -> " 89.1 " :)" CRLF

PRINT

The PRINT statement outputs the values passed to the output stream and then prints a line break. It's equivalent to using DISPLAY with a CRLF at the end.

Syntax:

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PRINT <multiple NUMBER, TEXT, TEXT-VAR, NUMBER-VAR or CRLF>

Example:

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PRINT "Hello, " nameVariable "! This is a number -> " 89.1 " :)"

ACCEPT _

The ACCEPT command is used to gather input from the user. If a TEXT variable is specified, anything the user enters before pressing the 'return' key will be accepted. If a NUMBER variable is specified, the user must enter a number (if any non-numeric key is entered, the error message "Redo from start" will be output and the ACCEPT command rerun).

Syntax:

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ACCEPT <TEXT-VAR or NUMBER-VAR>

EXECUTE _

The EXECUTE statement executes the specified system command.

Syntax:

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EXECUTE <TEXT or TEXT-VAR>

Example 1:

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# Prepare the command to execute
IN myTextVar JOIN "echo " myVariable " >> myFile"
# Execute it
EXECUTE myTextVar

Example 2:

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# Execute "dir" to list the files in the current directory under Windows
EXECUTE "dir"

EXECUTE _ AND STORE OUTPUT IN _

The EXECUTE - AND STORE OUTPUT IN executes the specified command and stores any resulting text in the passed variable.

Syntax:

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EXECUTE <TEXT or TEXT-VAR> AND STORE OUTPUT IN <TEXT-VAR>

EXECUTE _ AND STORE EXIT CODE IN _

The EXECUTE - AND STORE EXIT CODE IN executes the specified command and stores the exit code in the passed variable.

Syntax:

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EXECUTE <TEXT or TEXT-VAR> AND STORE EXIT CODE IN <NUM-VAR>

ACCEPT _ UNTIL EOF

The ACCEPT UNTIL EOF statement accepts input from standard input until an EOF state is reached and stores all data gathered in TEXT-VAR.

Syntax:

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ACCEPT <TEXT-VAR> UNTIL EOF

LOAD FILE _ IN _

The LOAD FILE statement loads the contents of a file into a text variable.

Syntax:

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LOAD FILE <TEXT or TEXT-VAR> IN <TEXT-VAR>

Example:

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LOAD FILE "myFolder/myTextFile.txt" IN myVariable

Error Codes:

If the LOAD operation should fail, the following values will be returned into the ERRORCODE and ERRORTEXT variables:

  • ERRORCODE: 1
  • ERRORTEXT: "The file '<filename>' couldn't be opened."

Warning

Always use the ERRORCODE variable to check if the operation was successful or not. Do not use ERRORTEXT for anything else than displaying the error found, as its contents may change in future releases of LDPL.

WRITE _ TO FILE _

The WRITE x TO FILE y statement writes the value of x to the file called y. If the file already exists, everything in it will be overwritten by x.

Syntax:

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WRITE <NUMBER or NUMBER-VAR or TEXT or TEXT-VAR> TO FILE <TEXT or TEXT-VAR>

Example:

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WRITE "Hello there!" TO FILE "hello.txt"

Error Codes:

If the WRITE operation should fail, the ERRORCODE and ERRORTEXT variables will be set to the following values:

  • ERRORCODE: 1
  • ERRORTEXT: "Could not open '<filename>'"
  • ERRORCODE: 2
  • ERRORTEXT: "Could not write to '<filename>'"

APPEND _ TO FILE _

The APPEND x TO FILE y statement appends the value of x to the file called y. If the file already exists, x will be added at the end of its contents.

Syntax:

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APPEND <NUMBER or NUMBER-VAR or TEXT or TEXT-VAR> TO FILE <TEXT or TEXT-VAR>

Example:

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APPEND "\nHow are you?" TO FILE "hello.txt"

in this case, the file hello.txt (created in the example of the WRITE _ TO FILE _ function and modified as stated there) will contain the text

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Hello there!
How are you?

Error Codes:

If the APPEND operation should fail, the ERRORCODE and ERRORTEXT variables will be set to the following values:

  • ERRORCODE: 1
  • ERRORTEXT: "Could not open '<filename>'"
  • ERRORCODE: 2
  • ERRORTEXT: "Could not write to '<filename>'"