Exercise 4-7. Write a routine ungets(s) that will push back an entire string onto the input. Should ungets know about buf and bufp, or should it just use ungetch? The answer is: ungets should use ungetch, not access buf and bufp directly. This is the principle of information hiding — getch and ungetch own the …
A C program to print factors of a number finds all positive integers that divide the number evenly (with no remainder). These are also called divisors. For 12: the factors are 1, 2, 3, 4, 6, and 12. Every number has at least two factors: 1 and itself. A number with exactly two factors is …
Exercise 2-2. Write a loop equivalent to the for loop below without using && or ||: for (i = 0; i < lim – 1 && (c = getchar()) != ‘\n’ && c != EOF; ++i) s[i] = c; Understanding the Problem The && operator in C is a short-circuit operator: if the left operand …
Exercise 1-23. Write a program to remove all comments from a C program. Don’t forget to handle quoted strings and character constants properly. C comments don’t nest. Approach The core challenge is that the same character sequence means completely different things depending on context. A /* inside a string literal is not a comment. A …
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 …
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