Same thing without the array: 

my $joined_string = '-' x 600;
foreach ( 1 .. 10 ) {
    my $i = int rand 600;
    redo if 'X' eq substr $joined_string, $i, 1;
    substr $joined_string, $i, 1, 'X';
}

[download]

In reply to Re^2: Difficulty in randomization by jwkrahn
in thread Difficulty in randomization by Anonymous Monk

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