Line Input #keyword

Reads one line of text from a file

Syntax

Line Input #file number, string_variable_1

Line Input #file number, string_variable_2 , max_length

Parameters

Name		Description
`file number`		file number of an file opened for `Input`
`string_variable_1`		variable-length or fixed_length (and known) string, to receive the line of text
`string_variable_2`		dereferenced {z\|w}string pointer or {z\|w}string variable passed by reference (string buffer size unknown for both), to receive the line of text
`max_length`		maximum number of characters allowed to be written to the string buffer, including the NULL terminator

Description

Reads a line from an open text file (opened for Input through a bound file number) and stores it in a string variable.

A line of text ends at, but does not include the end of line characters. An end of line character may be the LF character (Chr(10)) or the CRLF character pair (Chr(13,10)).

Two syntaxes are available:

The first syntax is only allowed when the string buffer size (provided by string_variable_1) is either variable or fixed (and known).
The second syntax with max_length parameter is only allowed when the string buffer size (provided by string_variable_2) is unknown. This happens for dereferenced ZString/WString pointers, or ZString/WString variables passed by reference. This can used to truncate the text line to be read, or avoid overflowing beyond allocated data of the provided string buffer.

Note:

- Using Line Input # is naturally dedicated to Input Access file mode.
- It is also allowed in Binary/Random Access file mode, but this was never well tested and results may vary.

Remarks

Version

Before fbc 1.10.0, the second syntax (with max_length parameter) was not supported.

Differences from QB

None

Example

Open "myfile.txt" For Output As #1

Print #1, "Hello, World"

Close #1



Dim s As String

Open "myfile.txt" For Input As #1

Line Input #1, s

Close #1

Print "'" & s & "'"



Const maxlength = 6  '' max 5 characters plus 1 null terminal character

Dim pz As ZString Ptr = CAllocate(maxlength, SizeOf(ZString))

Open "myfile.txt" For Input As #1

Line Input #1, *pz, maxlength

Close #1

Print "'" & *pz & "'"

Deallocate(pz)

Reference

Documented in KeyPgLineinputPp.html