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How to get a random line from a file

Posted on 2002-04-18
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Last Modified: 2010-03-05
How to get a random line from a file?

If found this at www.perl.com

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How do I select a random line from a file?  
Here's an algorithm from the Camel Book:

    srand;
    rand($.) < 1 && ($line = $_) while <>;  
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My file name will be test.txt

How to use this code. How to tell the script code what the file name is and what will be the result line?
 

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Question by:mmcw
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3 Comments
 
LVL 6

Expert Comment

by:andreif
ID: 6950433
In your code data is read from standatd input by "<>"
You can open your text file like usualy and change <> to <FileHandler>

So, code looks like:

open(F, "test.txt");
srand;
rand($.) < 1 && ($line = $_) while <F>;
close(F);


Result is in variable $line;

print $line;
0
 
LVL 6

Expert Comment

by:andreif
ID: 6968669
Please, let me know if this doesn't work or something is not clear
--------------------

In your code data is read from standatd input by "<>"
You can open your text file like usualy and change <> to <FileHandler>

So, code looks like:

open(F, "test.txt");
srand;
rand($.) < 1 && ($line = $_) while <F>;
close(F);


Result is in variable $line;

print $line;
0
 
LVL 6

Accepted Solution

by:
andreif earned 400 total points
ID: 6968670
Please, let me know if this doesn't work or something is not clear
--------------------

In your code data is read from standatd input by "<>"
You can open your text file like usualy and change <> to <FileHandler>

So, code looks like:

open(F, "test.txt");
srand;
rand($.) < 1 && ($line = $_) while <F>;
close(F);


Result is in variable $line;

print $line;
0

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