[Perl 範例代碼] 字串的 trim() 函式

轉載自 這裡 
前言 : 
在進行字串比對時, 常常因為開頭或結尾多了一個(或多個)空白而比對失敗, 那麼這個 trim() 函式便能幫上忙. 

範例代碼 : 

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1. #!/usr/bin/perl  
2.   
3. # Declare the subroutines  
4. sub trim($);  
5. sub ltrim($);  
6. sub rtrim($);  
7.   
8. # Create a test string  
9. my $string = "  \t  Hello world!   ";  
10.   
11. # Here is how to output the trimmed text "Hello world!"  
12. print trim($string)."\n";  
13. print ltrim($string)."\n";  
14. print rtrim($string)."\n";  
15.   
16. # Perl trim function to remove whitespace from the start and end of the string  
17. sub trim($)  
18. {  
19.     my $string = shift;  
20.     $string =~ s/^\s+//;  
21.     $string =~ s/\s+$//;  
22.     return $string;  
23. }  
24. # Left trim function to remove leading whitespace  
25. sub ltrim($)  
26. {  
27.     my $string = shift;  
28.     $string =~ s/^\s+//;  
29.     return $string;  
30. }  
31. # Right trim function to remove trailing whitespace  
32. sub rtrim($)  
33. {  
34.     my $string = shift;  
35.     $string =~ s/\s+$//;  
36.     return $string;  
37. }  

補充說明 : 
* Perl Regular Expressions By Example 
* Perl Black Book: The Most Comprehensive Perl Reference Available Today 
* Perl in a Nutshell