Exercise 1-14. Write a program to print a histogram of the frequencies of different characters in its input. Approach The key insight here is one of the most elegant idioms in C: a character read from getchar() is already an integer — its ASCII value. That value falls in the range 0–127, so it can …
Exercise 1-13. Write a program to print a histogram of the lengths of words in its input. It is easy to draw the histogram with the bars horizontal; a vertical orientation is more challenging. Approach The program breaks into two clear phases: counting word lengths, then rendering the histogram. Counting reuses the IN/OUT state machine …
Exercise 1-12. Write a program that prints its input one word per line. Approach A word is any contiguous run of non-whitespace characters; spaces, tabs, and newlines are all separators. The challenge is not reading words — it is knowing when to emit the newline that separates them in the output. The solution borrows the …
Exercise 1-11. How would you test the word count program? What kinds of input are most likely to uncover bugs if there are any? Exercise 1-11 has no new program to write. It asks you to think like a tester — to look at the word count program K&R presented in Section 1.5.4 and design …
Exercise 1-10. Write a program to copy its input to its output, replacing each tab by t, each backspace by b, and each backslash by \. This makes tabs and backspaces visible. Approach The exercise is deceptively simple to state but teaches something subtle about C: the difference between a character’s value in the program …
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