Exercises
See Appendix A for answers to the following exercises (remember, it’s normal to be surprised by some of the things that regular expressions do; that’s one reason that the exercises in this chapter are even more important than the others. Expect the unexpected):
[10] Make a program that prints each line of its input that mentions
fred. (It shouldn’t do anything for other lines of input.) Does it match if your input string isFred,frederick, orAlfred? Make a small text file with a few lines mentioning “fred flintstone” and his friends, then use that file as input to this program and the ones later in this section.[6] Modify the previous program to allow
Fredto match as well. Does it match now if your input string isFred,frederick, orAlfred? (Add lines with these names to the text file.)[6] Make a program that prints each line of its input that contains a period (
.), ignoring other lines of input. Try it on the small text file from the previous exercise: does it noticeMr. Slate?[8] Make a program that prints each line that has a word that is capitalized but not ALL capitalized. Does it match
Fredbut neitherfrednorFRED?[8] Make a program that prints each line that has a two of the same nonwhitespace characters next to each other. It should match lines that contain words such as
Mississippi,Bamm-Bamm, orllama.[8] Extra credit exercise: write a program that prints out any input line that mentions both
wilmaandfred.