读取文件检查顺序

Question

我正在读取这样的文件

1
one
2
two
3
three
three
three
four
five
5

在这篇文章中，我想检查序列one two three four five，并打印三次出现的次数。

我的代码：

use warnings;
use strict;
open(tempp1,"<$temp1") or die "Could not open file $temp1: $!";
my $count = 0;
while(my $line=<tempp1>) {
if ($line eq "one") {
while(my $line=<tempp1>) {
if ($line eq "two") {

while(my $line=<tempp1>) {
if ($line eq "three") {
$count++;
while(my $line=<tempp1>) {
if ($line eq "four") {
while(my $line=<tempp1>) {
if ($line eq "five") {
last;
}}}}}}}}}}
print "$countn";
close tempp1;

输出正在打印：1如何更正？

Answer 1

问题是，当您应该同时查找three和four时，一旦遇到three，就立即开始查找four。

简单的答案是取代

while(my $line=<tempp1>) {
if ($line eq "three") {
$count++;
while(my $line=<tempp1>) {
if ($line eq "four") {

带有

while(my $line=<tempp1>) {
if ($line eq "three") {
$count++;
while(my $line=<tempp1>) {
if ($line eq "three") {
$count++;
}
elsif ($line eq "four") {

但目前尚不清楚这是否会产生预期的结果。考虑以下输入：

# Possible Sequence 1   Possible Sequence 2
# -------------------   -------------------
one        # one                   one
two        # two                   two
three      # three                 three
three      # three                 three
four       # four                  
three      #                       three
three      #                       three
three      #                       three
four       #                       four
five       # five                  five
# -------------------   -------------------
# 2 instances           5 instances

count应该是2(找到four时停止计数(还是5(尽可能大(？上述解决方案将返回2。

此外，请注意，您目前没有检查是否找到了four和five，但您建议这是必需的。

Answer 2

ikegami的回答中指出了它不起作用的原因。

但是，作为一种替代方案，您可以考虑使用基于正则表达式的解决方案。

例如：

use strict;
use warnings;
my $file_content;
do { # we use a do block to change the line terminator locally
local $/ = undef; # set line terminator as undef so we will read whole file
# when we would try to read a line
open my $fh, '<', 'file.txt' or die $!;
$file_content = <$fh>; # now it reads the whole file
close $fh or die $!;
};
if ($file_content =~ m/ ^ oneR twoR ((?:threeR)+) fourR five $ /ixm) {
print "Number of 'three's is: " . split m/R/, $1;
print "n";
} else {
die 'I could not find a valid sequence';
}

(注意，由于这将读取整个文件，因此您需要足够的内存来保存它(

然后您尝试使用以下regex:来匹配文件内容

m/
^                     # start of line
oneR             # literal 'one' + end of line character/s
twoR 
((?:threeR)+)    # One or more (+) "three" + end of line repetitions
# everything holded on a capturing group (outer parentheses)
fourR 
five
$                     # end of line (a character is not required)
/ixm # i = ignore case
# x = ignore whitespace and allows comments
# m = ^ and $ match begin and enf of line (instead of begin and end of string)

它有两个用途：

• 检查是否找到有效的1、2、3。。。，4、5序列
• 捕获3。。。，3部分

3。。。，3部分在第一个捕获组($1(上捕获。然后按行分割内容，您拥有的行数就是three的数

Answer 3

我会查找这样的行。

use strict;
use warnings;
use English;
my $counter=0;
my $threes = 0;
my @lines_to_match = qw(one two three four five); 
open( my $fh , "<" , "file.txt") or die $OS_ERROR;
while ( my $line = readline($fh) )
{
if ( $counter < scalar(@lines_to_match) and $line =~m/$lines_to_match[$counter]/ )  
{
$counter++;
}
$threes++ if $line =~m/three/;
}
close($fh);
print "counter = $counter - threes = $threesn";

您可以检查是否所有项目都与匹配

print "true" if $counter == scalar(@lines_to_match);

你也可以检查最后一场比赛是"；三个"；通过使用以下之一

$threes++ if $line =~m/three/ and $counter==3;
$threes++ if $line =~m/three/ and $line=~ m/$lines_to_match[$counter-1]/;