Question

我有一个用perl编写的简单脚本，当我尝试运行时，我不断收到此特定错误。该脚本用于生成一些数字，用于检查整数到浮点。这是我得到的特殊错误。

Can't use an undefined value as an ARRAY reference at /tools/oss/packages/i86pc-5.10/perl/5.8.8-32/lib/5.8.8/Math/BigInt/Calc.pm line 1180

从错误消息中我无法弄清楚我的代码出错的地方。顺便说一下，我需要使用64位数字。我该如何调试此问题？

以下是代码示例

use bignum;
use warnings;
use strict;

open(VCVT, ">CvtIntToFp") or die "couldn't open file to write:$!";

my $number;
my $sgn;

# left with 31 bits excluding the sign
# 23 bits of significand needed, all the result
# will be exact except where leading bit ignoring singn is >23
# take its 2's complement to get the negative number  and put it
# into the register
# 32 bit number 1 bit sign 31 left any number with leading 1 @position >23 (counting from 0) will be inexact when in floating point
# 30-24 bit positons can have a leading ones at at any position and result is an inexact

my $twoPwr32 = 0x100000000; #2**32

my @num=();

for(my $i=0; $i<100; $i++)
{
    $sgn = (rand()%2);
    my $tempLead = (rand()%7); # there are 7 bits from 24 to 30
    $number=$tempLead << 24;
    if($sgn)
    {$number = ($twoPwr32- $number +1) & 0xffffffff;
    }
    $number = sprintf("%x", $number);
    push(@num, $number);
}
my $item=0;
foreach $item (@num)
{
    print "$item\n";
    print VCVT "$item\n";
}

Answer 1

尝试使用use diagnostics获取更好的错误消息并阅读perldoc bignum。给出了错误和解释，使用bignum在内部将数字转换为bignum并返回引用。由于我有perl 5.14文档，我有perl 5.20文档的链接，我认为该bug仍然存在。请参阅http://perldoc.perl.org/bignum.html

更新：

Hexadecimal number > 0xffffffff non-portable at throw_stack.pl line 19 (#1)
    (W portable) The hexadecimal number you specified is larger than 2**32-1
    (4294967295) and therefore non-portable between systems.  See
    perlport for more on portability concerns.

另请参阅this问题，了解Perl中64位算法的用法。

不能将未定义的值用作ARRAY引用

1 个答案: