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Re: read from a file and write into the same file

by DigitalKitty (Parson)
on Mar 02, 2008 at 20:15 UTC ( #671529=note: print w/ replies, xml ) Need Help??


in reply to read from a file and write into the same file

Hi Anonymous Monk.

Perl has numerous file modes from which to select:

#Open the 'txt' file for reading open FH, '<', "$file_name.txt" or die "Error:$!\n";
#Open the 'txt' file for writing. Creates the #file_name if it doesn't already exist #and will delete/overwrite a pre-existing file of the same name open FH, '>', "$file_name.txt" or die "Error:$!\n";
#Open the 'txt' file for appending. Creates the #file_name if it doesn't already exist open FH, '>>', "$file_name.txt" or die "Error:$!\n";
#Open the 'txt' file for a 'read/write'. #Will not create the file if it doesn't #already exist and will not delete/overwrite #a pre-existing file of the same name open FH, '+<', "$file_name.txt" or die "Error:$!\n";
#Open the 'txt' file for a 'read/write'. Will create #the file if it doesn't already exist and will #delete/overwrite a pre-existing file #of the same name open FH, '+>', "$file_name.txt" or die "Error:$!\n";
#Open the 'txt' file for a 'read/append'. Will create #the file if it doesn't already exist and will #not delete/overwrite a pre-existing file #of the same name open FH, '+>>', "$file_name.txt" or die "Error:$!\n";

A few suggestions:

Always enable both the strict and warnings pragmas with use strict; and use warnings; respectively. When you perform a file close operation, it is beneficial to check the success or failure since a hardware error could result:
close FH or die "Error in closing the file ", __FILE__, " $!\n";

Hope this helps,

~Katie


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