I/O Statements
Note
While this section is up-to-date and complete, it has to be reformated to be easier on the eyes. All UPPERCASE statement names and code should be changed to lowercase.
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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Example:
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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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EXECUTE _
The EXECUTE
statement executes the specified system command.
Syntax:
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Example 1:
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Example 2:
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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 _ 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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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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LOAD FILE _ IN _
The LOAD FILE
statement loads the contents of a file into a text variable.
Syntax:
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Example:
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Error Codes:
If the LOAD operation should fail, the following values will be returned into the ERRORCODE
and ERRORTEXT
variables:
ERRORCODE
: 1ERRORTEXT
: "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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Example:
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Error Codes:
If the WRITE operation should fail, the ERRORCODE
and ERRORTEXT
variables will be set to the following values:
ERRORCODE
: 1ERRORTEXT
: "Could not open '<filename>'"ERRORCODE
: 2ERRORTEXT
: "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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Example:
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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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Error Codes:
If the APPEND operation should fail, the ERRORCODE
and ERRORTEXT
variables will be set to the following values:
ERRORCODE
: 1ERRORTEXT
: "Could not open '<filename>'"ERRORCODE
: 2ERRORTEXT
: "Could not write to '<filename>'"