Exercises (Learning Perl, 3rd Edition)

2.13. Exercises

[5] Write a program that computes the circumference of a circle with a radius of 12.5. Circumference is 2 times the radius (approximately 2 times 3.141592654). The answer you get should be about 78.5.
[4] Modify the program from the previous exercise to prompt for and accept a radius from the person running the program. So, if the user enters 12.5 for the radius, she should get the same number as in the previous exercise.
[4] Modify the program from the previous exercise so that, if the user enters a number less than zero, the reported circumference will be zero, rather than negative.
[8] Write a program that prompts for and reads two numbers (on separate lines of input) and prints out the product of the two numbers multiplied together.
[8] Write a program that prompts for and reads a string and a number (on separate lines of input) and prints out the string the number of times indicated by the number on separate lines. (Hint: Use the "x" operator.) If the user enters "fred" and "3," the output should be three lines, each saying "fred". If the user enters "fred" and "299792," there may be a lot of output.