Worked Excercises from The C Programming Language, by Brian W. Kernignham and Dennis M. Ritchie

This repository contains solutions to the examples presented in the classic book The C Programming Language, by Brian W. Kerningham and Dennis M. Ritchie. In many cases they have been written to utilize C99 features. Solutions for any given chapter attempt to only use featured introduced up to that point in the book.

Kernighan and Ritchie The C Programming Language Code Examples

Cross-Platform Testing

So far, the code in this repository has only been complied and tested on Apple OS X El Capitan v10.11 using the clang compiler [Apple LLVM version 7.3.0 (clang-703.0.31)]. Additionally, I utilized the 'splint' linter (v3.1.2). If you want to compile these without splint, the Makefiles will need to be modified accordingly.

Chapter 1 - "A Tutorial Introduction"

• 1-01 - helloworld.c: Hello World
• 1-02 - escapechars.c: All escape characters
• 1-03 - ftoc.c: Fahrenheit-Celsius
• 1-04 - ctof.c: Celsius-Fahrenheit
• 1-05 - ftoc-reverse.c: Fahrenheit-Celsius in Reverse
• 1-06 - eofvalue.c: Determine the value of EOF returned by getchar() from stdin
• 1-07 - printeof.c: Print the value of EOF directly
• 1-08 - countchar.c: Count blanks, tabs, and new lines from stdin
• 1-09 - singleblank.c: Replace one or more blanks with a single blank
• 1-10 - showhiddens.c: Replaces tabs, backspaces, and backslashes by their escape characters
• 1-11 - countwords.c: Counts the number of words
• 1-12 - wordperline.c: Outputs its input one word per time
• 1-13 - wordhistohori.c: Horizontally-oriented histogram of the number of words

•  - wordhistovert.c:  Vertically-oriented histogram of the number of words
  

• 1-14 - charhistohori.c: Horizontally-oriented histogram of the number of characters

•  - charhistovert.c:  Vertically-oriented histogram of the number of characters
  

• 1-15 - ftoc-func.c: Fahrenheit-Celsius Table (using a function)
• 1-16 - longestline.c: Print arbitrarily long lines
• 1-17 - longlines.c: Prints lines longer than 80 characters
• 1-18 - cleantrailsnblanks.c: Cleans out trailing blanks and tabs. Eliminates blank lines.
• 1-19 - reverse.c: Reverses all input one line at a time
• 1-20 - detab.c: Replace tabs with blank spaces
• 1-21 - entab.c: Replaces converts spaces to tabs according to tab stops
• 1-22 - fold.c: Folds long lines to a specified width
• 1-23 - nocomment.c: Removes all comments from a C program
• 1-24 - minilint.c: Performs rudementary syntax checks on a C program

Chapter 2 - "Types, Operators, and Expressions"

• 2-01 - typelimits.c: Prints the ranges of each of the numeric types
• 2-02 - equivloop.c: For-loop equivalent to longestline without using logical operators
• 2-03 - htoi.c: Implements htoi() hexadecimal to integer converter
• 2-04 - squeeze.c: Implements squeze() which removes multiple chars from a string
• 2-05 - any.c: Implements any() which returns the position of a search char
• 2-06 - setbits.c: Implements setbits() which sets bits based upon a pattern
• 2-07 - invert.c: Implements invert() which inverts the bits starting at a position
• 2-08 - rightrot.c: Implements rightrot() which returns the value of a rotated integer
• 2-09 - fastbitcount.c: Implements a faster bitcount() using a two's complement property
• 2-10 - tolower.c: Implements a lower() using a trinary conditional

Chapter 3 - "Control Flow"

• 3-01 - binsearch.c: Implements a binary search with only one test inside the main loop
• 3-02 - escape.c: Tools to handle escape characters (bi-directionally)
• 3-03 - expand.c: Expands regex style string ranges (e.g. 'a-z')
• 3-04 - itoa.c: Version of itoa() that handles the largest negative integer
• 3-05 - itob.c: Implements itob() that converst a number to a string of a particular base
• 3-06 - itoaw.c: Implements itoaw() that cconvers number to string of a minimum width

Chapter 4 - "Functions and Program Structure"

• 4-01 - strrindex.c: Returns the position of the rightmost occurance of text in a string
• 4-02 - atof.c: Implements atof() string to double converter with scientific notation support
• 4-03 - rpncalc4-03/ RPN Calculator supporting modulus and negative number support
• 4-04 - rpncalc4-04/ RPN Calculator (rpncalc2) extended to include stack inspection and manipulation
• 4-05 - rpncalc4-05/ RPN Calculator (rpncalc3) extended to support math functions
• 4-06 - rpncalc4-06/ RPN Calculator (rpncalc4) extended to support variables
• 4-07 - ungets.c: Implements ungets() that returns a whole string to the input buffer
• 4-08 - singlegetch.c: Implements getch() and ungetch() that support just a single char buffer
• 4-09 - ungetseof.c: Implements getch(), ungetch(), and ungets() in a maner supporting EOF
• 4-10 - rpncalc4-10/ RPN Calculator (rpncalc5) based upon whole line handling
• 4-11 - rpncalc4-11/ RPN Calculator (rpncalc6) that uses 'static' to negate needing ungetch()
• 4-12 - itoarecursive.c: A recursive implementation of itoa()
• 4-13 - reverserecursive.c: A recursive implementation of reverse()
• 4-14 - swapmacro.c: A version of reverse() that uses a macro for swaping two values

Chapter 5 - "Pointers and Arrays"

• 5-01 - getint.c: Implements getint() that returns an integer (w/limit checks)
• 5-02 - getfloat.c: Implements getfloat() that returns a floating point
• 5-03 - strcat.c: Implements pointer version of strcat()
• 5-04 - strend.c: Implements strend() that returns true if one string is at the end of another
• 5-05 - strnfunc/ Implements library versions of library functions:
  • strncpy.c: strncpy()
  • strncat.c: strncat()
  • strncmp.c: strncmp()
• 5-06 - pointers/ Implements a pointer version of:
  • anyp.c: any()
  • atofp.c: atof()
  • cleantrailsnblanksp.c: cleantrailsnblanks()
  • escapep.c: escape()
  • expandp.c: expand()
  • htoip.c: htoi()
  • itoawp.c: itoaw()
  • itobp.c: itob()
  • longestlinep.c: longestline()
  • reversep.c: reverse()
  • reverserecursivep.c: reverserecursive()
  • squeezep.c: squeeze()
• 5-07 Supports array of pointer exercise (plus qsort and rudimentary 'alloc()' tests
  • readline.c: First version of readline that uses alloc() (c.f. section 5.6)
  • readline2.c: Alternate version for exercise 5-07. Compare timings with 'readline.c'
• 5-08 - datetools.c: Adds error checking to day_of_year() and month_day()
• 5-09 - datetoolsp.c: Implements day_of_year() and month_day() using pointers, added month_name()
• 5-10 - expr/ Command line version of RPN Calculator ("expr")
• 5-11
  • detab2.c: Replace tabs with blank spaces using a passed set of tab stops
  • entab2.c: Replaces converts spaces to tabs according to tab stops using a passed set of tab stops
• 5-12
  • detab3.c: Replace tabs with blank spaces using command switches to set intervals
  • entab3.c: Replaces converts spaces to tabs using command switches to set intervals
• 5-13 - tail2.c: Displays the specified number of lines from the end of a file
• 5-14 - sort1.c: Sorts input lines supporting reverse and numeric ordering using '-r' and '-n' switches
• 5-15 - sort2.c: Extends sort1.c to also support '-f' switch to fold upper and lower case
• 5-16 - sort3.c: Extends sort2.c to also support '-d' switch to sort by 'directory order'
• 5-17 - sort4.c: Extends sort3.c to also support for searching a fixed position field ('+pos1', '-pos1')
• 5-18 - dcl.c: Parses a C language pointer declaration (with some error handling)
• 5-19 - undcl.c: Converts (sort of) natural language into a C language pointer declaration
• 5-20 - dcl2.c: Extends dcl.c to support function argument types, qualifiers like const, etc

Chapter 6 - "Structures"

• 6-01 - getword.c: Gets next key word or character handling underscore, string constants, comments, and preprocessor control lines
• 6-02 - getvars.c: Prints variable names in a C program that are identical in the first 'X' characters (6 by default)
• 6-03 - wordxref.c: Cross-references words from stdin by line number excluding stop words
• 6-04 - wordfreq.c: Lists all the distinct words from stdin listed in decreasing frequency
• 6-05 - tablookup.c: Implements a hash table based table look-up set of functions
• 6-06 - define.c: Simple '#define' pre-processor

Chapter 7 - "Input and Output"

• 7-01 - chngcase.c: Transforms input to all upper or lower case based upon name of program ('lower' or 'upper')
• 7-02 - print.c: Prints a file with arbitrary contents in a reasonable way
• 7-03 - minprintf.c: Faux implementation of printf to demonstrate variable arguments
• 7-04 - minscanf.c: Faux implementation of scanf to introduce scanf
• 7-05 - scancalc/ A variation of whole line RPN calc from 4-10 that utilizes sscanf
• 7-06 - mindiff.c: Prints first line where two files differ
• 7-07 - minfind.c: Searches files lines either matching, or not matching, a pattern optional line numbers
• 7-08 - fprint.c: Prints a set of files with header, footer, page breaks, and page count

Chapter 8 - "The UNIX System Interface"

• 8-01 A minimal impact of cat which concatinates files using low-level OS calls
  • mincat.c: First version of mincat that uses low-level OS calls (c.f. sections 8.2, 8.3)
  • mincat2.c: Alternate version for exercise 8-01 using stdio calls--compare timings with 'mincat.c'
• 8-02 A version of minimal stdio functions implemented with fields instead of bits. Compare timings and size with minstdiotest.c.
  • stdiobits.c: Test program that excercises 'minstdio0'. Compare timings and size with 'minstdiotest.c'. Execution time in ticks is returned as the exit status (view with 'echo $?' after running).
  • minstdio0.h: Header for a minimal implementation of some 'stdio' library functions u