为什么在这个Perl函数中严格引用错误？

Question

最低代码

#!/usr/local/bin/perl
use strict;
use warnings;
use Math::Geometry::Planar qw(SegmentLineIntersection);

sub x_intercepts {
    my $xa = @{ $_[0] };
    my @xcross = ();
    my @x_axis = ( [0, 2000], [1, 2000] );

    foreach my $i (0 .. 1) {
        my $xc = SegmentLineIntersection([ @$xa[$i, $i + 1], @x_axis ]);
        push @xcross, $xc;
    }        
    return \@xcross;
}

my @xs = qw/22.595451 20.089094 17.380813 15.091260 12.477935 10.054821 7.270003 4.804673 4.728526 4.619254 4.526920 4.418416 4.321419 4.219890 4.123336 4.009777 3.912648 3.804183 3.705847 3.597756 3.512301 3.393413 3.301963 3.196725 3.098560 3.007482 2.899825 2.801002 2.688680 2.598862 2.496139 2.393526 2.282183 2.190449 2.084530 1.987778 1.877562 1.788788 1.678473 1.578123 1.467071 1.373372 1.283629 1.176670 1.071805 0.975422 0.877622 0.767820 0.667409 0.562480 0.469068 0.354589 0.264291 0.152522 0.063765 -0.045323 -0.136783 -0.248559 -0.343694 -0.459178 -0.551917 -0.640803 -0.755502 -0.845535 -0.955227 -1.045879 -1.155600 -1.254556 -1.365163 -1.461669 -1.571370 -1.658043 -1.772672 -1.865942 -1.981037 -2.073702 -2.176205 -2.276184 -2.367371 -2.476278 -2.567385 -2.686326 -2.777433 -2.884357 -2.980067 -3.087754 -3.183607 -3.291003 -3.386942 -3.495822 -3.586759 -3.702955 -3.793550 -3.900680 -3.999672 -4.093094 -4.200047 -4.301026 -4.399742 -4.493190 -4.602013 -4.705124 -4.812383 -4.907510 -5.022904 -5.109829 -5.214304 -5.317662 -7.703172 -10.350131 -12.921361 -15.431203 -18.188013 -20.544248 -22.822808 -25.679854 -22.999092 -20.540434 -17.964916 -15.398857 -12.990375 -10.402209 -7.888263 -5.504909 -5.217892 -5.109841 -5.014187 -4.908558 -4.811807 -4.704282 -4.605555 -4.504613 -4.406546 -4.292540 -4.204043 -4.088770 -3.995524 -3.905669 -3.796544 -3.707958 -3.596449 -3.490966 -3.382869 -3.293054 -3.185821 -3.088417 -2.971214 -2.880314 -2.772518 -2.677986 -2.569794 -2.473668 -2.365096 -2.276422 -2.179232 -2.068195 -1.973110 -1.859565 -1.771873 -1.669422 -1.569953 -1.462626 -1.364911 -1.258100 -1.159318 -1.050486 -0.959979 -0.849149 -0.749421 -0.640950 -0.547122 -0.451754 -0.344463 -0.252269 -0.134625 -0.051640 0.052970 0.154112 0.266505 0.353926 0.468739 0.561666 0.673810 0.759169 0.881697 0.973207 1.082409 1.170424 1.282163 1.378096 1.472728 1.586454 1.678473 1.785688 1.873862 1.984090 2.086021 2.196799 2.292400 2.386097 2.493190 2.601726 2.694346 2.803450 2.901878 3.011959 3.103050 3.196979 3.294507 3.397563 3.504076 3.600163 3.712539 3.809573 3.919799 4.012314 4.120694 4.216406 4.322895 4.416466 4.522871 4.623917 4.735925 4.826929 7.361253 9.647208 12.337984 14.870260 17.439730 19.921717 22.524080 25.125903/;

foreach my $i ( x_intercepts(@xs) ) {
    print "$i \n";
}

这使

在test5.pl第8行使用"strict refs"时,不能使用字符串("22.595451")作为ARRAY引用.

在声明变量时,这里的基本错误.my main::$xa = main::$xa;在初始化中声明不是要走的路.

为什么会出现这个错误？

Answer 1

您正在读取传递给函数(22.595451)的第一个参数,该函数是一个字符串,并且正在尝试将其视为一个数组(它不是).

据推测,您打算将数组引用作为单个参数传递,而不是将数组的每个成员作为单独的参数传递.

x_intercepts(\@xs)

将arrayref转换为常规数组后,您似乎尝试将其视为标量:

my $xa = @{ $_[0] };

这没有意义.

根据您以后的操作,看起来您想$ax成为一个arrayref,所以不要取消引用它:

my $xa = $_[0];