printing problem

[mama12]

Hallo,

I have a printing error, I can not print 2500 random DNA (A C T G).

can some one here fix my problem

best regards
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#!/usr/bin/perl -w

# 2500 random bases

print "ask for file name: ";


$filename = <STDIN>;

open BN, ">$filename";

my@DNA = ('A','C','G','T');

my $DNA;

for (1 .. 2500) {

$DNA = $DNA[int(rand(length(@DNA)))];
}
print BN "$DNA\n";

close BN;

exit;

 

[eewah]

Hi,mama12.

just some mistake in ur code:

$filename = <STDIN>;

open BN, ">$filename";
my @DNA = ('A','C','G','T');
my $DNA;

for (1 .. 2500) {

$DNA = $DNA[int(rand([red]scalar[/red] @DNA))];
[blue]print BN "$DNA\n"[/blue];

}

close BN;

U cant use length to get number of elements in an array. (use scalar instead)

 

[mama12]

thanXXXX eewah,

thank u for ur help

 

[stevexff]

Normally scalar is redundant - perl is smart enough to work out that if you are using an array in a scalar context, then you must want the number of elements. So for example

for (my i = 0; i < @array; i++;) {
    # do stuff involving $i here
}

will work fine. It's only when you have a context that accepts a list, like

print scalar @array;

that you need to coerce it explicitly with scalar.

Steve

[small]"Every program can be reduced by one instruction, and every program has at least one bug. Therefore, any program can be reduced to one instruction which doesn't work." (Object:erlDesignPatterns)[/small]

 

[KevinADC]

also: length() is for strings, not arrays. I am not sure what perl will return if you try that with an array.