Laboratory: File Processing

Summary: This laboratory provides experience with reading data from and writing data to text files.

Prerequisites: Familiarity with Strings in C. Familiarity with basic I/O operations in C.

• Preparation
• Exercises
  • Exercise 1: Small Cats
  • Exercise 2: Other Small Cats
  • Exercise 3: Fixing Small Cats
  • Exercise 4: Choosing Cats
  • Exercise 5: Crazy Cats
  • Exercise 6: Copy Cats
  • Exercise 7: Curious Cats
  • Exercise 8: Checking Cats
  • Exercise 9: Testing Cats

Preparation

Exercises

Exercise 1: Small Cats

Write a small C program called kitten.c that reads a text file and prints its contents to stdout. You should implement kitten using fgetc and fputc (or just putc). You should take the name of the file from the command line.

The output from kitten file should be the same as the output from cat file, provided file exists.

You may assume that no line in the input file will contain more than 256 characters.

Don't forget to close the file when you are done!

Exercise 2: Other Small Cats

Write a small C program called kitty.c that has the same behavior as kitten.c but that uses fgets and fputs (or puts) rather than fgetc and fputc.

Exercise 3: Fixing Small Cats

Determine what changes do you need to make to kitten.c and kitty.c to support longer lines?

You may want to discuss those changes with your class mentor or teacher.

Exercise 4: Choosing Cats

Which of kitten.c and cat.c do you prefer? Why?

Exercise 5: Crazy Cats

Write a program, kat, that repeatedly reads the name of a file from standard input and then prints the contents of that file to standard output. (That is, the user may enter multiple file names and each file gets concatenated to output.)

Exercise 6: Copy Cats

Write a small C program called cpy.c that reads two file names from the command line, a source and a destination. Your program should then read the source file and copy its contents to the destination file.

Exercise 7: Curious Cats

Write a small C program called cktc.c that reads two strings from the command line, a string to search for and a filename to search in. Your program should read the file, search for the target string in each input line, and then copy just those lines which contain the target to stdout.

You may find the C library function strstr useful for this exercise. It is declared in <string.h>.

Exercise 8: Checking Cats

Experience suggests that most students will not put error checking in the previous programs. Please add checking so that the programs report appropriate error messages, such as when asked to read a file that does not exist.

Exercise 9: Testing Cats

With a classmate, determine how you might implement unit tests for the procedures we just wrote. You need not implement those unit tests, but you should be prepared to describe your strategy to the class.