Perl学习笔记(4)文件的输出输入

1. 文件名前面没有">"表示读文件 open(FILE,"C:test.txt"); while(<FILE>) { ? ? ? ? chomp; ? ? ? ? print "$_n"; } close(FILE); 2. 文件名前面有一个">"表示写文件，并覆盖原有内容 open(FILE,">C:test.txt"); print FILE "大家好n"; close(FILE); 3. 文件名前面有两个">"表示在这个文件后面追加内容 open(FILE,">>C:test.txt"); print FILE "大家好n"; close(FILE); 4. 一次性将文件中的所有内容读入一个数组中(该方法适合小文件)： open(FILE,"filename")||die"can not open the file: $!"; @filelist=<FILE>; foreach $eachline (@filelist) { ? ? ? ? chomp $eachline; } close FILE; @filelist=<FILE>; 当文件很大时，可能会出现"out of memory"错误，这是可以采用如下方法，一次读取一行。 5. 一次从文件中读取一行，一行行地读取和处理(读取大文件时比较方便)：? open(FILE,"filename")||die"can not open the file: $!"; while (defined ($eachline =<FILE>)) { ? ? ?chomp $eachline; ? ? ? ? ?# do what u want here! } close FILE; 6. STDIN,STDOUT,STDERR and DATA - Perl file handles STDIN - Standard Input,for user control input,typically the keyboard STDOUT - Standard Output,for regular use output,typically the screen STDERR - Standard Error,for error output; typically defaults to the screen too ? 例print STDERR "this is an apple.";? DATA - Input for data stored after __END__ at the end of the program