Question

我对perl很新这是我正在做的事情，我有这样的输入行我想替换匹配的每一行的值字符串通过传递变量名，变量值和替换值作为命令行的输入参数

     input_data:
     total_sum  0x0C    Uint8,unsigned char     
     num     0x0D   Uint8,unsigned char     
     max    0x4A    Uint8,unsigned char     
     padd   0x00    Uint8,unsigned char     
     ideal  0x01    Uint16, unsigned short
     min    0xffdd7f Uint16, unsigned short

预期产出：

     1.total_sum    0x0C    Uint8,unsigned char  //change 0x0B with 0x0C
     2.also if the string conation Uin16 then I need to pad 0x00 as i 
        want to read only one byte at a time
        for e.g ideal should be pad with (0x00,0x01)
     3.also if the string contain value more than one byte then i need 
        to split with 1 byte each
        for e.g oxffdd7f should be (0x0ff,0xdd,0x7f)

代码：

    #! /usr/bin/env perl

     use strict;
     use warnings;
     # input variable pass as a input argument
     my $variable_name =shift @ARGV;
     # variable value pass as a input argument
     my $variable_value =shift @ARGV;
     #variable value need to be replaced with new value 
     my $Replacement_var = shift @ARGV;
     # Name of the file the data is in
     my $input_filename  = 'my_input.txt';
     # Name of the file you want to dump the output to
     my $output_filename = 'my_output.txt';

     open my $input_fh, "<", $input_filename or die $!; 
     my @array;   
     while (my $eachline = <$input_fh>)
     {
     if ($eachline=~/^$variable_name/ and /$variable_value/)
        {
         $eachline=s/$variable_value/$Replacement_var/ ;
        }
        #here  extracting only hex values from each line
        while ($eachline =~ m/(0x(?:[0-9]|[A-f])+)/gi)  
        {
          push @array, $1;
        }
     }

     close $input_fh;
     open my $output_fh, ">", $output_filename or die $!;
     print {$output_fh} join(", ", @array);

我正在检查变量名称和值，然后替换变量值使用新的但没有发生替换（field_ind 0x0B-＆gt; 0x0C）请帮助我，我在做错了。

Answer 1

$eachline=~/^$variable_name/ and /$variable_value/

应该是

$eachline=~/^$variable_name/ and $eachline=~/$variable_value/

当绑定运算符（=~）未明确用于正则表达式的左侧时，Perl会将其隐式绑定到$_变量。

您还想在其他地方使用绑定运算符并说

$eachline =~ s/$variable_value/$Replacement_var/ ;

而不是

$eachline = s/$variable_value/$Replacement_var/ ;

命令行替换，新值无效

1 个答案: