LINE INPUT #n Statement

Syntax

Description

Reads an entire line of text from the file associated with file number #n into a STRING variable, discarding the trailing line-ending characters (CR, LF, or CRLF). Unlike INPUT #n, LINE INPUT does not interpret commas or quotes as delimiters—the entire line is read verbatim.

The V13 implementation uses a character-by-character read loop that correctly handles all common line-ending conventions: CR+LF (Windows), LF-only (Unix), and CR-only (classic Mac). V19 adds encoding-aware reading: when the file is opened with ENCODING UTF16LE or ENCODING UTF16LE_BOM, LINE INPUT reads UTF-16 code units and converts them to UTF-8-compatible ANSI for STRING targets.

Parameters

Example

FUNCTION PBMAIN() AS LONG
    LOCAL ln AS STRING
    LOCAL lineNum AS LONG

    lineNum = 0
    OPEN "data.txt" FOR INPUT AS #1
    WHILE NOT EOF(1)
        INCR lineNum
        LINE INPUT #1, ln
        PRINT "Line "; lineNum; ": "; ln
    WEND
    CLOSE #1
    FUNCTION = 0
END FUNCTION

Encoding-Aware Example V19

' Read a UTF-16LE encoded file with BOM
OPEN "unicode.txt" FOR INPUT ENCODING UTF16LE_BOM AS #1
LINE INPUT #1, s$     ' reads UTF-16LE, converts to ANSI/UTF-8 STRING
PRINT s$
CLOSE #1

Line Ending Behavior

Generated Assembly

Character-by-Character Read Loop (V13)

; Read one byte at a time until CR, LF, or EOF
__pb_liread_loop:
mov    rcx, [rbp - handle_offset]        ; file handle
lea    rdx, [rbp - one_byte_temp]         ; single-byte buffer
mov    r8, 1                              ; read exactly 1 byte
lea    r9, [rbp - bytes_read]             ; &bytesRead
mov    [rsp + 32], 0                      ; lpOverlapped = NULL
call   [__imp_ReadFile]
cmp    rax, 0                             ; ReadFile returns 0 on failure
je     __pb_liread_eof                    ; treat as EOF
mov    al, byte [rbp - one_byte_temp]     ; load the byte
cmp    al, 13                             ; is it CR?
je     __pb_liread_check_lf               ; maybe CRLF ahead
cmp    al, 10                             ; is it LF?
je     __pb_liread_done                   ; line complete (LF-only)

; Not a line ending: store the byte
lea    rdi, [rbp - linebuf_offset]        ; output buffer
add    rdi, [rbp - linebuf_pos]           ; current write position
mov    [rdi], al                          ; store byte
inc    qword [rbp - linebuf_pos]          ; advance position
jmp    __pb_liread_loop                   ; read next byte

__pb_liread_check_lf:
; CR found. Peek ahead for LF (CRLF handling).
mov    rcx, [rbp - handle_offset]
lea    rdx, [rbp - one_byte_temp]
mov    r8, 1
lea    r9, [rbp - bytes_read]
mov    [rsp + 32], 0
call   [__imp_ReadFile]
cmp    rax, 0
je     __pb_liread_done                   ; CR at EOF
mov    al, byte [rbp - one_byte_temp]
cmp    al, 10                             ; LF follows CR?
je     __pb_liread_done                   ; consume the LF
; Not LF: push it back conceptually (simple approach: ignore)
__pb_liread_done:
; NUL-terminate the line buffer
mov    r10, [rbp - linebuf_pos]
lea    r11, [rbp - linebuf_offset]
add    r11, r10
mov    byte [r11], 0                      ; buffer[pos] = 0
; Assign the NUL-terminated buffer to target STRING variable

__pb_liread_eof:
; EOF reached before any line ending
; Just NUL-terminate whatever was accumulated and return

UTF-16LE Encoding-Aware Read V19

; When ENCODING UTF16LE or UTF16LE_BOM is set:
; 1. Read 2 bytes at a time (one UTF-16 code unit)
; 2. Convert UTF-16LE code unit to multi-byte UTF-8 sequence
; 3. Check for CR (0x000D) and LF (0x000A) as 16-bit values
; 4. When line ending found, convert accumulated UTF-16LE to ANSI STRING
;    using WideCharToMultiByte(CP_ACP, 0, wbuf, wlen, buf, buflen, 0, 0)

Comparison: INPUT# vs LINE INPUT#

Imported WinAPI Functions

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