Textfile read line 7 (snippet)

[Sver]

fileName$ ="test.txt"
requiredLine =7

open fileName$ for input as #i
f$ =input$( #i, lof( #i))
close #i

line7$ =word$( f$, 7, chr$( 13))
if line7$ =chr$( 13) +chr$( 10) or line7$ ="" then notice "Empty line! ( or file has fewer lines)."

print line7$



[tsh73]

Interesting idea
But according to Help file, on two delimiters word$ return delimiter for empty item.
So eimpty for chr$(13) should be chr$(13)
(and in Windows, lined elimiter is CRLF, so empty line retrned chr$(10) instead)
(anyway, line7$ was never going to be chr$( 13) +chr$( 10))

So I rewrote thungs a bit. Now it prints three variants:

Line 3 is empty line.
File test.txt has fewer lines then 7
Required line #: 2
>113<

fileName$ ="test.txt"
requiredLine =2

CRLF$=chr$( 13)+chr$( 10)

open fileName$ for input as #i
f$ =input$( #i, lof( #i))
close #i

reqLine$ =word$( f$, requiredLine, CRLF$)

select case  reqLine$
case CRLF$
   print "Line "; requiredLine ;" is empty line."
case ""
   print  "File ";fileName$;" has fewer lines then "; requiredLine
case else
   print "Required line #: ";requiredLine
   print ">";reqLine$;"<"
end select


[Sver]

, Thanks. The enter en the line feed makes it difficult. When we can read a line, then we can write or change a (new) line

'(re)write a line in test.txt

'one
'two
'three
'four

linenumber=2   'no zero !
newtext$="two changed"
file$="test.txt"
'----
open file$ for input as #i
   f$ =input$( #i, lof( #i))
close #i
'-----------------------------------------------------

print instr(f$, chr$(13)), " enter"
print instr(f$, chr$(10)), " line feed"
print

' find startpos line
start=0
for i=1 to linenumber-1
start=instr(f$, chr$(10), start+1) 'upto chr$ line feed
next
'--------------------------------------------------------
print start, "startposition line x"

firststring$=left$(f$,start)   'incl enter+ line feed chr$

print
print firststring$, "string upto line x"
print len(firststring$),"incl enter and line feed"
print

endpos=0
for i=1 to linenumber
endpos=instr(f$, chr$(13), endpos+1)
next

print endpos, "end line x without enter and line feed"

lengfile=len(f$)
print lengfile, "total lenght file f$"

aft=lengfile - endpos+1
print aft

laststring$=right$(f$,aft)

print laststring$, "string after line x"
print instr(laststring$, chr$(13)), " enter"   'have to be 1
print instr(laststring$, chr$(10)), " line feed"    'have to be 2
print

f$= firststring$+newtext$+laststring$

print f$

open file$ for output as #i
print #i, f$
close #i

end



[Sver]

Small addition
'------------------------------(re)write a line in test.txt----------------------

linenumber=3   'no zero !
newtext$="three"
file$="test.txt"
----
if linenumber=0 then notice "linenumber=0"

open file$ for input as #i
   f$ =input$( #i, lof( #i))
close #i
'-----------------------------------------------------
'find startpos line
start=0
for i=1 to linenumber-1
start=instr(f$, chr$(10), start+1) 'upto chr$ line feed
next
'--------------------------------------------------------
'string$ before line
firststring$=left$(f$,start)   'incl enter+ line feed chr$
'-------
endpos=0
for i=1 to linenumber
endpos=instr(f$, chr$(13), endpos+1)
next

lengfile=len(f$)
if endpos=0 then endpos=lengfile+1 'chrs not found/ no line -    add !
'----------------------
'string$ after line
aft=lengfile - endpos+1
laststring$=right$(f$,aft)
'---------------
'new$ string
f$= firststring$+newtext$+laststring$

open file$ for output as #i
print #i, f$
close #i