[C Programming] Exercises on Pointer and Array

We cover exercises on Pointer and Array in book "The C programming language".

Longest line

Exercise 1-16. Revise the main routine of the longest-line program so it will correctly print the length of arbitrary long input lines, and as much as possible of the text.
Solution

Exercise 1-17. Write a program to print all input lines that are longer than 80 characters.
Solution

Exercise 1-18. Write a program to remove trailing blanks and tabs from each line of input, and to delete entirely blank lines.
Solution

Exercise 1-19. Write a function reverse(s) that reverses the character string s. Use it to write a program that reverses its input a line at a time.
Solution


Count digits

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.
Solution

Exercise 1-14. Write a program to print a histogram of the frequencies of different characters in its input.
Solution

Get Int

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

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

Strlen

Strcpy

Strcmp

Exercise 5-3. Write 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

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

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

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

Quicksoft

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

Day of year

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

Month name

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

Pattern-finding 

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 * (3+4).
Solution

Exercise 5-11. Modify the program 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

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

Exercise 5-13. Write the program tail, which prints the last n lines of its input. By default, n is set to 10, let us 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

Qsort

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

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

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

Exercise 5-17. Add a field-searching capability, so sorting may bee 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

Parse Declarator

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

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

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