Perl——正则表达式(四) 查找替换s///

转自http://blog.csdn.net/blog_abel/article/details/40589227 侵删

一. 介绍

使用 s/regex/replacement/modifiers 进行查找替换

二. 实例

(1) s///

$f = "'quoted words'";  
#进行模式匹配,下面方法去除''单引号  
if($f =~ s/^'(.*)'$/$1/) { #true, $1指的是引用了第一组(.*)的内容, ^$这两个字符用来表示开始与结束  
  
    print "matches","
"; # mathces  
    print $f,"
";        # quoted words  
                          # 注意 标量$f 匹配后本身内容发生了变化  
}  

(2) s///r

用它进行匹配后,原始标量的值不会发生变化，可以把新值赋值给一个新的标量

$f = "'quoted words'";  
#进行模式匹配,下面方法去除''单引号  
$n = $f =~ s/^'(.*)'$/$1/r;  
  
print "matches","
";  
print $f,"
"; # quoted words   # 注意 标量$f 匹配后本身内容无变化  
      
print $n,"
"; # 'quoted words' # 注意 $n  

 

(3) s///g 多次查找替换

$z = "time hcat to feed the cat hcat";  
$z =~ s/cat/AAA/g;#替换多次  
print $z,"
"; #结果为 time hAAA to feed the AAA hAAA  

 

(4) s///e 求值

# reverse all the words in a string  
$x = "the cat in the hat";  
$x =~ s/(w+)/reverse $1/ge; # $x contains "eht tac ni eht tah"  
  
# convert percentage to decimal  
$x = "A 39% hit rate";  
$x =~ s!(d+)%!$1/100!e; # $x contains "A 0.39 hit rate"  

(5) s/// 可以用 s!!! , s{}{} , s{}// 进行替换