**“C Programming Language (2nd Edition)“**popularly known as K & R C book.

In this blog post I will give links to all the exercises from Chapter 5 of the book for easy reference.

**Chapter 5: Pointers and Arrays**

**Exercise 5-1.**As written, getint treats a + or – not followed by a digit as a valid representation of zero. Fix it to push such a character back on the input.

Solution to Exercise 5-1.**Exercise 5-2.**Write getfloat , the floating-point analog of getint . What type does getfloat return as its function value?

Solution to Exercise 5-2.**Exercise 5-3.**GWrite a pointer version of the function strcat that we showed in Chapter 2: strcat(s,t) copies the string t to the end of s .

Solution to Exercise 5-3.**Exercise 5-4.**Write the function strend(s,t) , which returns 1 if the string t occurs at the end of the string s , and zero otherwise.

Solution to Exercise 5-4.**Exercise 5-5.**Write versions of the library functions strncpy , strncat , and strncmp , which operate on at most the first n characters of their argument strings. For example, strncpy(s,t,n) copies at most n characters of t to s . Full descriptions are in Appendix B.

Solution to Exercise 5-5.**Exercise 5-6.**Rewrite appropriate programs from earlier chapters and exercises with pointers instead of array indexing. Good possibilities include getline (Chapters 1 and 4), atoi , itoa , and their variants (Chapters 2, 3, and 4), reverse (Chapter 3), and strindex and getop (Chapter 4).

Solution to Exercise 5-6.**Exercise 5-7.**Rewrite readlines to store lines in an array supplied by main , rather than calling alloc to maintain storage. How much faster is the program?

Solution to Exercise 5-7.**Exercise 5-8.**There is no error-checking in day_of_year or month_day. Remedy this defect.

Solution to Exercise 5-8.**Exercise 5-9.**Rewrite the routines day_of_year and month_day with pointers instead of indexing.

Solution to Exercise 5-9.**Exercise 5-10.**Write the program expr , which evaluates a reverse Polish expression from the command line, where each operator or operand is a separate argument. For example, expr 2 3 4 + * evaluates 2 X (3+4).

Solution to Exercise 5-10.**Exercise 5-11.**Modify the programs entab and detab (written as exercises in Chapter 1) to accept a list of tab stops as arguments. Use the default tab settings if there are no arguments.

Solution to Exercise 5-11.**Exercise 5-12.**Extend entab and detab to accept the shorthand entab -m +n to mean tab stops every n columns, starting at column m . Choose convenient (for the user) default behavior.

Solution to Exercise 5-12.**Exercise 5-13.**Write the program tail, which prints the last n lines of its input. By default, n is 10, say, but it can be changed by an optional argument, so that tail -n prints the last n lines. The program should behave rationally no matter how unreasonable the input or the value of n. Write the program so it makes the best use of available storage; lines should be stored as in the sorting program of Section 5.6, not in a two-dimensional array of fixed size.

Solution to Exercise 5-13.**Exercise 5-14.**Modify the sort program to handle a -r flag, which indicates sorting in reverse (decreasing) order. Be sure that -r works with -n.

Solution to Exercise 5-14.**Exercise 5-15.**Add the option -f to fold upper and lower case together, so that case distinctions are not made during sorting; for example, a and A compare equal.

Solution to Exercise 5-15.**Exercise 5-16.**Add the -d (“directory order”) option, which makes comparisons only on letters, numbers and blanks. Make sure it works in conjunction with -f .

Solution to Exercise 5-16.**Exercise 5-17.**Add a field-handling capability, so sorting may be done on fields within lines, each field sorted according to an independent set of options. (The index for this book was sorted with -df for the index category and -n for the page numbers.)

Solution to Exercise 5-10.**Exercise 5-18.**Make dcl recover from input errors.

Solution to Exercise 5-18.**Exercise 5-19.**Modify undcl so that it does not add redundant parentheses to declarations.

Solution to Exercise 5-19.**Exercise 5-20.**Expand dcl to handle declarations with function argument types, qualifiers like const , and so on.

Solution to Exercise 5-20.

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