Learning Perl chapter 4 练习题-白红宇

原文发表在网易博客 2010-11-06 13:07:36

第1题和第2题

#!perl -w

#chapter 4 , exercise one and two

use strict;

sub total{

my $sum;

foreach $_ (@_){

$sum += $_;

}

$sum;

}

my @fred=(1,3,5,7,9);

print "sum of (@fred) is:\t ",&total(@fred),"\n";

print "sum of 1 to 100 is :\t",&total(1..100),"\n";

第3题

#!perl -w

#chapter 4 , exercise 3

use strict;

sub getSum{

my $sum=0;

foreach $_ (@_){

$sum+=$_;

}

$sum;

}

sub getAverage{

my @abovelist=();

my $length=@_;

my $average=-1;

$average=&getSum(@_)/$length;

}

sub above_average{

my @abovelist;

my $average=&getAverage(@_);

foreach $_ (@_){

if($_ > $average){

push @abovelist, $_

}

return @abovelist;

}

my @fred=&above_average(1..10);

print "above the average in one to ten is :(@fred)\n";

第4题

#!perl -w

use strict;

use 5.010;

sub greet1{

state $lastPerson="";

if(@_ ==1 ){

if($lastPerson ne ""){

print "Hi,$_[0]!$lastPerson is also here.\n";

}else{

print "Hi,$_[0]!You are the first one here!\n";

}

$lastPerson=$_[0];

}

&greet1("leipei");

&greet1("ada");

第5题

#!perl -w

use strict;

use 5.010;

sub greet2{

state @personlist;

if(@_ == 1){

if(@personlist >0){

print "Hi,$_[0]! I have seen:@personlist\n";

}else{

print "Hi,$_[0]! You are the firt one here.\n";

}

push (@personlist,$_[0]);

}

greet2("Fred");

greet2("Barney");

greet2("Wilma");

greet2("Betty");

本文转自leipei博客园博客，原文链接：http://www.cnblogs.com/leipei2352/archive/2011/05/25/2057471.html，如需转载请自行联系原作者