changing some lines in a file

[Peter Posselt Vestergaard]

Hi again, and thanks for your answer, but it doesn't seem to help.
What I meant by stopping was that I have tried to put some prints
different places(se below), and it won't print anything out after the
problematic line. 
Best regards
Peter Vestergaard

db = open("db.dat","r")                                          
data = db.readlines()
db.close

found=0
for i in range(len(data)):
    line = data[i]
    if found==1:
        if line[0:2]=='fi':
            print data[i]
            data[i] = 'fi=' + Form["fi"].value
            print data[i]
        elif line[0:2]=='la':
            line='la='+Form["la"].value
        elif line[0:2]=='em':
            line='em='+Form["em"].value
        elif line[0:2]=='ho':
            line='ho='+Form["ho"].value
        elif line[0:2]=='st':
            line='st='+Form["st"].value
            found=2
    if line[0:9]==('id='+Form["id"].value):
        found=1
if found==0:
    print '<H1>Fejl i årskortnummeret!</H1>'
    stop 
#udskift databasen med den ændrede version
db = open("db.dat","w")
db.writelines(data)
db.close


Gordon McMillan wrote:
> 
> Peter Posselt Vestergaard writes:
> 
> > Hi, I'm quite a newbie in Python-programming, so I hope you'll
> > forgive me asking about some pretty things. :-) My problem is that I
> > have a file in which i want to find some lines and replace them with
> > some other data. I've tried a lot of things but nothing seems to
> > work.
> 
> Unfortunately, you haven't said what "doesn't work" means.
> 
> > Below is my best try, but it seems that the script stops when
> > it is about to execute the line:
> 
> Stops how? With a traceback?
> 
> > line=('fi='+Form["fi"].value)
> >
> > I'll be thankfull for any kind of help.
> > Best regards
> >
> > Peter Vestergaard
> >
> > ------------------------------------------------------------------
> >
> >
> > db = open("db.dat","r+")
> 
> Why are you opening for update?
> 
> > data = db.readlines()
> > db.close
> 
> MIssing something?
> 
> >
> > found=0
> > for line in data:
> >     print found
> >     if found==1:
> >         if line[0:2]=='fi':
> >             line=('fi='+Form["fi"].value)
> 
> Ah. Well you'll never see any results, because you're rebinding the
> variable "line" to a new string. When you return to the "for", you
> lose all your hard work.
> 
> You can either modify the data list by using
> 
> for i in range(len(data)):
>   line = data[i]
>   .....
>      data[i] = 'fi=' + Form[whatever]....
> 
> Or create a new list and append the modified lines to it.
> 
> (Updating a file in place usually means lots of seek()s and tells()
> and is basically never worthwhile on text files.)
> 
> >         elif line[0:2]=='la':
> >             line='la='+Form["la"].value
> >         elif line[0:2]=='em':
> >             line='em='+Form["em"].value
> >         elif line[0:2]=='ho':
> >             line='ho='+Form["ho"].value
> >         elif line[0:2]=='st':
> >             line='st='+Form["st"].value
> >             found=2
> >     if line[0:9]==('id='+Form["id"].value):
> >         found=1
> > if found==0:
> >     print '<H1>Fejl i årskortnummeret!</H1>'
> >     stop
> >
> > db = open("db.dat","w")
> > db.writelines(data)
> > db.close
> >
> > --
> > http://www.python.org/mailman/listinfo/python-list
> 
> - Gordon

-- 
Med venlig hilsen
Peter Posselt Vestergaard