Perl练习题DOC.docx

1、Perl练习题DOC2.12 练习写一个程序，计算半径为12.5的圆的周长。圆周长等于2（约为3.1415926）乘以半径。答案为78.5。 #!/usr/bin/perl$r=12.5;$pai=3.1415926;$C=2*$pai*$r;Print “$Cn”;修改上述程序，用户可以在程序运行时输入半径。如果，用户输入12.5，则应得到和上题一样的结果。 #!/usr/bin/perl$r=;$pai=3.1415926;$C=2*$pai*$r;Print “$Cn”;修改上述程序，当用户输入小于0 的数字时，程序输出的周长为0，而非负数。 #!/usr/bin/perl$r=;$pa

2、i=3.1415926;if($r=0)$C=2*$pai*$r;If($r0)$C=0;Print “$Cn”;写一个程序，用户能输入2 个数字（不在同一行）。输出为这两个数的积。#!/usr/bim/perl$a=;$b=;$c=$a*$b;Print”$c”;写一个程序，用户能输入1 个字符串和一个数字(n)（不在同一行）。输出为，n 行这个字符串，1 次1 行（提示，使用“x”操作符）。例如，如果用户输入的是“fred”和“3”,则输出为：3 行，每一行均为fred。如果输入为“fred”和“299792”,则输出为299792 行，每一行均为fred。 #!/usr.bin/perl

3、$string=;$int=;$output=$string x $intprint $output;3.9练习写一个程序，将一些字符串（不同的行）读入一个列表中，逆向输出它。如果是从键盘输入的，那在Unix 系统中应当使用CTRL+D 表明end-of-file，在Windows 系统中使用CTRL+Z. 写一个程序，读入一串数字（一个数字一行），将和这些数字对应的人名（下面列出的）输出来。（将下面的人名列表写入代码中）。fred betty barney dino Wilma pebbles bamm-bamm例如，当输入为1，2，4 和2，则输出的为fred, betty, dino,

4、和betty 写一个程序，将一些字符串（在不同的行中）读入一个列表中。然后按ASCII 顺序将它们输出来。也就是说，当输入的字符串为fred, barney, wilma, betty，则输出为barney betty fred wilma。分别在一行或不同的行将之输出。 1:#!/usr/bin/perl -wmichael=reverse();print michael;或：#!/usr/bin/perl -wuserinput=;foreach (userinput)unshift (array,$_);print array is arrayn;2:#!/usr/bin/perlnam

5、e=qw(fred betty barney dino Wilma pebbles bamm-bamm);number=;foreach (number)print $name$_-1n;3:#!/usr/bin/perlarray=;array=sort array;print array;4.11练习写一个名为&total 的子程序，返回一列数字的和。提示：子程序不应当有任何的I/O 操作；它处理调用的参数，返回处理后的值给调用者。结合下面的程序来练习，它检测此子程序是否正常工作。第一组数组之和我25。my fred = qw 1 3 5 7 9 ;my $fred_total = &to

6、tal(fred);print The total of fred is $fred_total.n;print Enter some numbers on separate lines: ;my $user_total = &total();print The total of those numbers is $user_total.n; 利用上题的子程序，写一个程序计算从1 到1000 的数字的和。 额外的练习：写一个子程序，名为&above_average，将一列数字作为其参数，返回所有大于平均值的数字（提示：另外写一个子程序来计算平均值，总和除以数字的个数）。利用下面的程序进行测试：

7、my fred = &above_average(1.10);print fred is fredn;print (Should be 6 7 8 9 10)n;my barney = &above_average(100, 1.10);print barney is barneyn;print (Should be just 100)n; 1:#!/usr/bin/perl -w#Date:2009-6-12# Exercise 4-1use strict;sub total my $sum=shift _; foreach (_) $sum=$sum+$_; $sum;my fred=qw

8、 1 3 5 7 9;my $fred_total=&total(fred);print The Total of fred is $fred_total.n;print Enter some numbers on separate lines: ;my $user_total = &total();print The Total of those numbers is $user_total.n;2:#!/usr/bin/perl -w#Date:2009-6-12# Exercise 4-2use strict;sub total my $sum=shift _; foreach (_)

9、$sum=$sum+$_; $sum;my array=1 . 1000;my $array_total=&total(array);print The sum of 1 to 1000 is $array_total.n;3:#!/usr/bin/perl -w#Date:2009-6-12# Exercise 4-3use strict;sub average my $number=_; my $sum=shift _; foreach (_) $sum=$sum+$_; my $array_average=$sum/$number;sub above_average my above;

10、foreach (_) if ($_&average(_) push above,$_; above;my above_fred = &above_average(1 . 10);print The above average of fred is above_fredn;my above_barney = &above_average(100, 1 . 10);print The above average of barney is above_barneyn;5.11练习写一个程序，类似于cat，但保持输出的顺序关系。（某些系统的名字可能是tac。）如果运行此程序：./tac fred b

11、arney betty, 输出将是文件betty 的内容，从最后一行到第一行，然后是barney, 最后是fred, 同样是从最后一行到第一行。（注意使用./确保调用的是你自己的程序，而非系统提供的） 写一个程序，要求用户在不同的行中输入一些字符串，将此字符串打印出来，规则是：每一条占20 个字符宽度，右对齐。为了确保正确的输出，在开头打印出一串数字作为比较（帮助调试）。注意，不要犯19 个字符宽度的错误。例如，如果输入，hello, good-bye，则输出为：123456789012345678901234567890123456789012345678901234567890 hello

12、 good-bye 修改上一个程序，允许用户选择宽度，如，用户输入30，hello, good-bye(在不同的行中)，则每一行的宽度为30。（提示：参阅第二章相应部分）。提示，如果选择的宽度太长，可以增加比较行的长度。 1:#!/usr/bin/perl -w#Date:2009-6-18# Exercise 5-1print reverse ;2-3:#!/usr/bin/perl -w#Date:2009-6-18# Exercise 5-2print What column width would you like?;chomp (my $width = );print Enter s

13、ome lines, then press Ctrl+D:n;chomp (my line = );print 1234567890 x ($width+9)/10), n;foreach (line) printf %$widthsn, $_;chapter21.-/home/confish/perl/girth#!/usr/bin/perl -w#this program calculate a circles girth#confishubuntu7.10$r=12.5;$g=12.5*2*3.1415;print the girth of the circle is $gn;-/hom

14、e/confish/perl/girth2.-/home/confish/perl/girthpro#!/usr/bin/perl -w#a better one to calculate girth#confishubuntu7.10printenter the radius of the circlen;chomp($r=);if($r0) printthe girth of the circle is .$r*2*3.1415.n; else printnonavailable!n; -/home/confish/perl/girthpro3.-/home/confish/perl/gi

15、rthzero#!/usr/bin/perl -w#calculate the girth and print 0 when the radius is lower than 0#confishubuntu7.10printenter the radius of the linen;chomp($r=);if($r0) printthe girth of the circle is $r*2*3.1415n; else printthe girth of the circle is 0n; -/home/confish/perl/girthzero4.-/home/confish/perl/p

16、roduct#!/usr/bin/perl -w#print the two numbers product#confishubuntu7.10printenter the two numbers:n;chomp($m=);chomp($n=);printthe product of the two numbers are .$m*$n.n;-/home/confish/perl/product5.-/home/confish/perl/printer#!/usr/bin/perl -w#print a string certain times depend on the usrs input

17、#confishubuntu7.10printenter a string and a number:n;$str=;chomp($num=);print $strx$num;-/home/confish/perl/printerchapter31.-/home/confish/reprint#!/usr/bin/perl -w#read some input and print them in reverse sequence#confishubuntu7.10print enter the string please:n;str=reverse ;print nthe reverse st

18、rings are:nstr;-/home/confish/reprint2.-/home/confish/num_to_name#!/usr/bin/perl -w#read some numbers and output the match name#confishubuntu7.10 $i=0;names=qw /fred betty barney dino Wilma pebbles bamm-bamm/;printenter the numbers please:n;chomp(nums=);foreach(nums) re=names; while($i ne $_) $n=shi

19、ft( re); $i+; $i=0; print $n,n; -/home/confish/num_to_name3.-/home/confish/sort_str#!/usr/bin/perl -w#read some strings and sort them in ASCII#confishubuntu7.10chomp(str=sort);#str=sort; will print them in diffrent linesprint str,n;-/home/confish/sort_strchapter41.-/home/confish/perl/subr#!/usr/bin/

20、perl -w#a subroutine named total returns sum of numbers#confishubuntu7.10sub total foreach $n(0.$#_) $sum+=$_$n; $sum; myfred=qw1 3 5 7 9;my $fred_total=&total(fred);printThe total of fred is $fred_total.n;printEnter some numbers on separate lines:n;my $user_total=&total();printThe total of those nu

21、mbers is $user_total.n;-/home/confish/perl/subr2.-/home/confish/perl/suber#!/usr/bin/perl -w#use the subroutine in last program to get the sum of 1.1000#confishubuntu7.10sub total foreach $n(0.$#_) $sum+=$_$n; $sum; num=(1.1000);$sum=&total(num);printThe sum of 1.1000 is $sumn;-/home/confish/perl/su

22、ber3.-/home/confish/perl/aver#!/usr/bin/perl -w#to print the number which is larger than the average#in some numbers#confishubuntu7.10sub average foreach $n(0.$#_) $sum+=$_$n; $average=$sum/($#_+1); sub above_average num=_; aba=(); $av=&average(num); foreach $n(0.$#_) if($_$n$av) push ( aba,$_$n); a

23、ba; my fred=&above_average(1.10);printfred is fredn;print(Shuold be 6 7 8 9 10)n;my barney=&above_average(100,1.10);printbarney is barneyn;print(Should be just 100)n;-/home/confish/perl/averchapter51.-/home/confish/perl/tac#!/usr/bin/perl -w#a prog same as cat but reverse the string#confishubuntu7.1

24、0ARGV=reverse ARGV;a=reverse;print a;-/home/confish/perl/tac2.-/home/confish/perl/20str#!/usr/bin/perl -w#a prog that print the strings as 20 words flush right#confishubuntu7.10str=;while($i!=5) foreach(0.9) print; $i+; printn;foreach(str) printf %21s,$_; -/home/confish/perl/20str3.-/home/confish/pe

25、rl/20strpro#!/usr/bin/perl -w#a prog print the strings as number usr apionted words flush right#confishubuntu7.10str=;while($i!=5) foreach(0.9) print; $i+; print n;$num=shift str;chomp $num;$conv=%.+$num.s;foreach(str) printf $conv,$_; -/home/confish/perl/20strprochapter61.-/home/confish/perl/hash#!/usr/bin/perl -w#hashs that print the names family name#confishu