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Perl文件读写

时间:2014-07-15 09:47:39      阅读:222      评论:0      收藏:0      [点我收藏+]

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Perl File Handling: open, read, write and close files

#====================

Opening files

Solution 1:

Opening a file in perl

open FILE, "filename.txt" or die $!; # read

open FILEHANDLE, MODE, EXPR

The available modes are the following:

modeoperandcreatetruncate
read <    
write > ? ?
append >> ?  

Each of the above modes can also be prefixed with the + character to allow for simultaneous reading and writing.

modeoperandcreatetruncate
read/write +<    
read/write +> ? ?
read/append +>> ?  

open FILE, ">", "filename.txt" or die $!    #write

open FILE, ">filename.txt" or die $!;   #write

Solution 2:

#!/usr/bin/perl

open(FILE, "<file.txt") or die "Couldn‘t open file file.txt, $!";

while(<FILE>){
   print "$_";
}

Following is the table which gives possible values of different modes

EntitiesDefinition
< or r Read Only Access
> or w Creates, Writes, and Truncates
>> or a Writes, Appends, and Creates
+< or r+ Reads and Writes
+> or w+ Reads, Writes, Creates, and Truncates
+>> or a+ Reads, Writes, Appends, and Creates

Solution 3:

 

sysopen(FILE, "file.txt", O_RDWR|O_TRUNC );

Following is the table which gives possible values of MODE

EntitiesDefinition
O_RDWR Read and Write
O_RDONLY Read Only
O_WRONLY Write Only
O_CREAT Create the file
O_APPEND Append the file
O_TRUNC Truncate the file
O_EXCL Stops if file already exists
O_NONBLOCK Non-Blocking usability

 

 

#====================

 

Reading files

read a text file line-by-line

my @lines = <FILE>;

while (<FILE>) { print $_; }

while (my $line = <FILE>) { ...}

read a file only a few characters at a time

open FILE, "picture.jpg" or die $!; # read

binmode FILE;

my ($buf, $data, $n);

while (($n = read FILE, $data, 4) != 0)

{ print "$n bytes read\n"; $buf .= $data; }

close(FILE);

#====================

Writing files

open FILE, ">file.txt" or die $!; #write

print FILE $str;

close FILE;

#====================

Closing files

open FILE1, "file.txt" or die $!; # read

open FILE2, "picture.jpg" or die $!; # read

...

close FILE2;

close FILE1;

 #====================

REF:

http://www.perlfect.com/articles/perlfile.shtml

 

 

Perl文件读写,布布扣,bubuko.com

Perl文件读写

标签:des   style   http   color   strong   文件   

原文地址:http://www.cnblogs.com/emanlee/p/3843925.html

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