perl如何查找字符串的个数

jackbrown

我们有一个txt文件

1. TAGAGCCTAGAAAAAAGTTACATGA 1250 1 chrY:11921135 F
   
2. GAAAAACAGGAACATTGTAGAGGAA 1250 1 chrY:11780373 F

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如何找出里面AAAA的个数，其中AAAAAA表示有3个AAAA

我本来是这样写的

1. #!/usr/bin/perl
   
2. open(ctr,'sss.txt')||die("Could not open sss.txt");
   
3. $text=<ctr>;
   
4. while($text)
   
5. {
   
6.         $count++ while $text =~/AAAA/g;
   
7.         $text=<ctr>;
   
8. }
   
9. print"the number of AAAA is $count";
   
10. close ctr;
    

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但发现那种重复的好像不能正确的计算，不知道应该如何改进？

shijiang1130

回复 1# jackbrown

是和?=有关的.我找找啊

shijiang1130

1. #!/usr/bin/perl
   
2. open(ctr,'sss.txt')||die("Could not open sss.txt");
   
3. $text=<ctr>;
   
4. while($text)
   
5. {
   
6.         $count++ while $text =~/(?=AAAA)/g;
   
7.         $text=<ctr>;
   
8. }
   
9. print"the number of AAAA is $count";
   
10. close ctr;

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回复 2# shijiang1130

jackbrown

回复 3# shijiang1130


    真是谢谢呀，弄了很长时间也不会！这次终于会了！

longjinjiu

I tried this:

my $count = 0;
while($str =~ /A{4,}/sg)
{
        $count += length($&) - 3;
}
print $count;

alleva

学习了

toniz

开拓下思维吧，应该还有蛮多写法的。

1. $text='asdfasAAAAAADSFAAAADFDSAFEA AAAAA';
   
2. $text =~/(?{$count++ })AAAA(?!)/;
   
3. print"the number of AAAA is $count";

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Bruceh2010

答案是多少啊楼主 ,是4么?

小鹭

$str="TAAAGAGCCTAGAAAAAAGTTACATGA 1250 1 chrY:11921135 F";
$count = $str =~ s/AAA//g;
print "$count\n";

DIYBYPERL

这样应该可以：

1. $_='TAAAAAGAGCCTAGAAAAAAGTTACATGA 1250 1 chrY:11921135 F';
   
2. print scalar ( ()=/A(?=AAA)/g ),"\n";

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