在Perl中将字符串与"eq"进行比较vs"==" [英] String compare in Perl with "eq" vs "=="

问题描述

我(一个完整的Perl新手)正在if语句中进行字符串比较:

I am (a complete Perl newbie) doing string compare in an if statement:

如果我执行以下操作:

if ($str1 == "taste" && $str2 == "waste") { }

我看到了正确的结果(即，如果条件匹配，它将评估"then"块).但是我看到了这些警告:

I see the correct result (i.e. if the condition matches, it evaluates the "then" block). But I see these warnings:

在行号x的数字eq(==)中，参数"taste"不是数字.
在行号x的数字eq(==)中，参数"waste"不是数字.

Argument "taste" isn't numeric in numeric eq (==) at line number x.
Argument "waste" isn't numeric in numeric eq (==) at line number x.

但如果我这样做:

if ($str1 eq "taste" && $str2 eq "waste") { }

即使满足if条件，也不会评估"then"块.

Even if the if condition is satisfied, it doesn't evaluate the "then" block.

在这里，$str1是taste，$str2是waste.

我该如何解决?

推荐答案

首先， eq 用于比较字符串； == 用于比较数字.

First, eq is for comparing strings; == is for comparing numbers.

即使满足"if"条件，也不会评估"then"块.

Even if the "if" condition is satisfied, it doesn't evaluate the "then" block.

我认为您的问题是您的变量不包含您认为的变量.我认为您的$str1或$str2包含"taste \ n"之类的内容.通过在 if :print "str1='$str1'\n";之前打印进行检查.

I think your problem is that your variables don't contain what you think they do. I think your $str1 or $str2 contains something like "taste\n" or so. Check them by printing before your if: print "str1='$str1'\n";.

可以使用chomp($str1);函数删除尾随的换行符.

The trailing newline can be removed with the chomp($str1); function.

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