Another Perl Practice(ActivePerl On Window Platform)-优快云博客

本文介绍了一个简单的程序，用于计算给定半径的圆的周长。程序首先定义了π的值，然后通过用户输入半径来计算不同大小的圆的周长。如果输入的半径小于零，则会提示错误并设周长为0。

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#

# Program to calculate the circumference of circle

# The constant variable of PI
$pi = 3.14159265;

# This section is to calculate the circumference of circle
# (whose radius is 12.5)
$radius = 12.5;

$cc = 2*$pi*$radius;

print $cc;
print "\n";

print "The circumference of circle(radius=$radius): $cc\n";

print "The circumference of circle(radius=".$radius."): ".$cc."\n";

# This section is to calculate the circumference of circle,
# which the radius of circle inputed from termine by user.
# So, pls enter the radius of circle while "Pls input the radius of circle".
# User can exit the program by click <ENTER> key.
print "Pls input the radius of circle:";
while ($radius = <STDIN>) {
    if ($radius eq "\n") {
        print "exit";
        last;
    }

    if ($radius < 0) {
        print "Warn: The radius of circle can not be less than zero(0)\n";
        $cc = 0;
    } else {
        $cc = 2*$pi*$radius;
    }
    print "The circumference of circle(radius=".$radius."): ".$cc."\n";

    #continue yes/no
    print "Pls input the radius of circle:";
}