將文本文件讀入perl中的陣列

Question

my $file = '/var/tmp/temp_data.txt';  ##################### File for reading 
    open(FILE, '<:encoding(UTF-8)', $file) || die("Unable to open file"); 
    my @fieldss = <FILE>; 
    close(FILE); 
    chomp @fieldss; 

    my @fields = split(':', @fieldss);####################### Splitting the lines in file ############## 
####################################### Dereference ############################ 
    my $names = $fields[0]; 
    my $rate = $fields[1]; 
    my $no_of_days = $fields[2]; 
    my $total_salary = $fields[3]; 
    my $total = $fields[4]; 
    my $basic = $fields[5]; 
    my $da = $fields[6]; 
    my $hra = $fields[7]; 
    my $ot_hallowance = $fields[8]; 
    my $gross = $fields[9]; 
    my $epf = $fields[10]; 
    my $nett = $fields[11]; 

    print "$names\n $rate\n"; 

     foreach $names (@fields) { 
       my $dbh = "DBI:$platform:$database:$host:$port"; 
       my $connect = DBI->connect($dbh, $user, $pw) || die $DBI::errstr; 
       $query = "SELECT * FROM salary WHERE name IN('sssss', 'ffffff', 'dddddd', 'ddededed', 'garaead', 'adgfdfg', 'gadfredg')"; 
       my $sth = $connect->prepare($query); 
       $sth->execute() || die $DBI::errstr; 

       my @data2; 
       while (@data2 = $sth->fetchrow_array()) { 
        my $name = $data2[0]; 
        my $email = $data2[1]; 

         if ($names eq $name) { ######################### Comparing names in file and database ######################## 

上面的代碼是讀取文本文件和數據使用split函數進行拆分。我的問題是我在閱讀和分割文件時犯了錯誤。我在運行代碼時遇到了504錯誤，我認爲這是因爲在文本文件中爲每一行調用數據庫。謝謝你的幫助。

Answer 1

這將有助於查看輸入文件中的數據是什麼樣子。但是在你的代碼中肯定會有一些奇怪的事情發生。主要的問題似乎是這一行：

my @fields = split(':', @fieldss); 

split()需要兩個標量參數 - 一個正則表達式拆就和一個字符串分割。因此，它在標量上下文中計算@fieldss並獲取數組中元素的數量。當然，這將是一個整數，不包含冒號。這導致@fields包含單個元素，這是@fieldss中元素的數量。這個例子說明：

use Data::Dumper; 

my @arr = qw[1:foo 2:bar 3:baz]; 

my @arr2 = split /:/, @arr; 

say Dumper @arr2; 

我得到的輸出是：

$VAR1 = '3'; 

你的代碼來設置@fields或許應該更多這樣的：

my $file = '/var/tmp/temp_data.txt'; 
open(my $fh, '<:encoding(UTF-8)', $file) 
    # Note: Added filename and error code to output. 
    || die("Unable to open $file: $!"); 

my @fields; 
while (<$fh>) { 
    chomp; 
    push @fields, split /:/; 
} 
close $fh; 

我沒有看過在你的代碼的其餘部分詳細介紹，但它肯定會提出一些問題。您的陣列到各個變量的複製可能是毫無意義的，但可以在單個語句來實現：

my ($names, $rate, $no_of_days, $total_salary, $total, 
    $basic, $da, $hra, $ot_hallowance, $gross, $epf, 
    $nett) = @fields; 

但你遍歷@fields，看似假設每個元素的名稱。也許你需要更詳細地解釋你在做什麼。

但是，這些都不能解釋您獲得的504狀態碼。您提到您正在爲文本文件中的每一行運行數據庫查詢。在你的循環的每次迭代中，你確實是一樣的查詢 - 這似乎是非常浪費的（只運行一次並將結果存儲在一個變量中），但是，因爲我們已經確定@fields只能做到包含一個元素，你的循環只運行一次，你只能查詢一次數據庫。

嚴格來說，這可能不是您的問題的答案。但是你的問題留下了太多無法解釋的事情，無法回答。希望這會給你一些洞見，說明你如何能夠改善你的計劃，以至於我們可以開始解決目前隱藏的真實問題。

更新：我剛剛意識到輸入文件的結構是什麼。你可能想把它讀成使用這樣的代碼散列的數組：

my $file = '/var/tmp/temp_data.txt'; 
open(my $fh, '<:encoding(UTF-8)', $file) 
    # Note: Added filename and error code to output. 
    || die("Unable to open $file: $!"); 

my @records; # Terrible variable name! 
my @cols = qw[names rate no_of_days total_salary total basic da 
       hra ot_hallowance gross epf nett]; 

while (<$fh>) { 
    chomp; 
    my %rec; 
    @rec{@cols} = split /:/; 
    push @records, \%rec; 
} 

Answer 2

我甚至不知道你的文件的樣子。但是在將蛋白質數據庫（PDB）文件讀入數組之前，我已經完成了這種類型的事情，然後將它們按照與我的空白分開的列分開。我不能保證我的代碼可以工作，因爲我甚至沒有你的文件，但無論如何，問題是你如何閱讀文件，然後將其分成列是問題，是的...

您的分割不起作用，因爲您不分割，但是您的分隔列可能是逗號或至少一個空格。但是我從來沒有在文件中看到像你說的冒號分隔的列。此外，是的，你可以將文件讀入數組中，但要將所有列作爲每行的標量，我認爲您需要在循環中繼續執行此操作，否則每個列的值都不會擴展所有的文件。好的，你真的分裂了冒號。我對這個麻煩感到抱歉。請原諒我。

#!/usr/bin/env perl 
# Program Description: _________ 
use strict; 
use warnings; 
use feature 'say'; # say is like print, but you don't need to type \n. 

my $file = '/var/tmp/temp_data.txt';  ##################### File for reading 
my $filehandle; # Just like your bareword filehandle FILE. 
my @fields =(); # My use of fields is the same as yours. 
open($filehandle, '<', $file) or die "Could not open file $_ because $!"; 

my @All_Lines = <$filehandle>; # This is just everything in the file ... all lines. 
my $line; # Our current line which will be useful for the split. 
close $filehandle; 

# We will declare all of our variables outside of a loop 
# That we split all the columns of the file on on colon. 
# ... declaring our variables now so they don't get locked in our loop. 
my $names; 
my $rate; 
my $no_of_days; 
my $total_salary; 
my $total; 
my $basic; 
my $da; 
my $hra; 
my $ot_hallowance; 
my $gross; 
my $epf; 
my $nett; 

# Iterating over ever line of the file in a foreach loop. 
foreach $line (@All_Lines) 
{ 

    @fields = split(':', $line); # splitting on a colon. 

$names = $fields[0]; 
$rate = $fields[1]; 
$no_of_days = $fields[2]; 
$total_salary = $fields[3]; 
$total = $fields[4]; 
$basic = $fields[5]; 
$da = $fields[6]; 
$hra = $fields[7]; 
$ot_hallowance = $fields[8]; 
$gross = $fields[9]; 
$epf = $fields[10]; 
$nett = $fields[11]; 

say "$names $rate"; 

# Then I'm pretty sure that I can dump the rest of your code here 
# And you should because @fields is now within this foreach loop. It doesn't exist anywhere else. 
# I'm pretty sure I'm justified in removing your foreach loop here 
# Because in mine, the column of names will be read and operated on line by line. 
# Also, your goal was to iterate over $names with a foreach loop 
# which I'm doing right now, but where are you operating on it? 

     # Perhaps you should declare these variables with "my" before we start looping through all the lines of the file one line at a time. 
     # But I think you will be okay having them here. 
     my $dbh = "DBI:$platform:$database:$host:$port"; 
     my $connect = DBI->connect($dbh, $user, $pw) || die $DBI::errstr; 
     # You didn't declare query with "my $query". I think you should, especially since I classically enabled "use strict". 
     $query = "SELECT * FROM salary WHERE name IN('sssss', 'ffffff', 'dddddd', 'ddededed', 'garaead', 'adgfdfg', 'gadfredg')"; 
     my $sth = $connect->prepare($query); 
     $sth->execute() || die $DBI::errstr; 

     my @data2; 
     # So @data2 gets formed when you start the while loop, right? 
     while (@data2 = $sth->fetchrow_array()) 
       { 
        my $name = $data2[0]; 
        my $email = $data2[1]; 

         if ($names eq $name) 
         { 
           ######################### Comparing names in file and database ######################## 
         } # This bracket ends your if conditional 
       } # This bracket ends your while loop. 

} # This bracket ends my foreach loop that you want to stay within. 

# Note: Commenting where brackets begin and end can be really useful when you are trying to stay within a loop. 

注：I測試基於上的文件 一個或多個空白分割其是PDB文件看起來像這樣由一個或多個白空間分離，並且PDB文件的每一列可以被逐行隔離，所以我很肯定這會在你的文件上起作用。

ATOM  38 CB PHE A 7  15.240 41.685 54.772 1.00 10.03   C 
ATOM  39 CG PHE A 7  15.740 42.936 54.063 1.00 12.39   C 
ATOM  40 CD1 PHE A 7  15.096 44.166 54.328 1.00 11.59   C 
ATOM  41 CD2 PHE A 7  16.851 42.864 53.189 1.00 10.59   C 
ATOM  42 CE1 PHE A 7  15.540 45.310 53.626 1.00 12.79   C 
ATOM  43 CE2 PHE A 7  17.329 44.058 52.581 1.00 13.07   C 
ATOM  44 CZ PHE A 7  16.651 45.259 52.776 1.00 12.33   C 
ATOM 156 CG GLU A 20  14.635 48.596 50.249 1.00 9.28   C 
ATOM 157 CD GLU A 20  15.173 49.229 51.481 1.00 10.96   C 
ATOM 158 OE1 GLU A 20  15.790 50.279 51.395 1.00 11.04   O 
ATOM 159 OE2 GLU A 20  14.851 48.625 52.550 1.00 13.31   O 

現在，我通常會在程序的後面關閉一個文件的方式，但是您是對的。即使在關閉文件後，也可以將其保存到數組中並逐行操作該數組。