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Our getch and ungetch do not handle a pushed-back EOF correctly. Decide what their properties ought to be if an EOF is pushed back, then implement your design. Solution by Franz Fritsche. (Comment: The solution is virtually identical with the solution given by Tondo/Gimpel in their C Answer Book. Alas, what can I do?) /* K&R Exercise 4-9 */ /* Franz Fritsche */ #include #define BUFSIZE 100 int b..

Answer to Exercise 4-8, page 79 Solution by Steven Huang Suppose there will never be more than one character of pushback. Modify getch and ungetch accordingly. /* K&R Exercise 4-8 */ /* Steven Huang */ #include int buf = EOF; /* buffer for ungetch */ int getch(void) /* get a (possibly pushed back) character */ { int temp; if (buf != EOF) { temp = buf; buf = EOF; } else { temp = getchar(); } retu..

Answer to Exercise 4-7, page 79 Solution by Steven Huang 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 ? /* K&R Exercise 4-7 */ /* Steven Huang */ #include #include #define BUFSIZE 100 char buf[BUFSIZE]; /* buffer for ungetch */ int bufp = 0; /* next free position in buf */ int getch(void) /* g..

Answer to Exercise 4-6, page 79 Solution by Bob Wightman Add commands for handling variables. (It's easy to provide twenty-six variables with single-letter names.) Add a variable for the most recently printed value. #include #include #include #include #include #define MAXOP 100 #define NUMBER 0 /* 4-6 these are new for this exercise*/ #define IDENTIFIER 1 #define ENDSTRING 2 /* 4-6 end of new st..

Answer to Exercise 4-5, page 79 Solution by Bob Wightman Add access to library functions like sin , exp , and pow . See in Appendix B, Section 4. #include #include #include #include #include #define MAXOP 100 #define NUMBER 0 #define IDENTIFIER 1 #define TRUE 1 #define FALSE 0 /* The new additions deal with adding functions from math.h to the calculator. In anticipation of the following exercise..

Answer to Exercise 4-4, page 79 Solution by Bob Wightman Add commands to print the top element of the stack without popping, to duplicate it, and to swap the top two elements. Add a command to clear the stack. #include #include #include #include #define MAXOP 100 #define NUMBER 0 #define TRUE 1 #define FALSE 0 /* This programme is a basic calculator. Extra cases have been added to: 1. Show the t..

Answer to Exercise 4-3, page 79 Solution by Bob Wightman Given the basic framework, it's straightforward to extend the calculator. Add the modulus ( % ) operator and provisions for negative numbers. In Bob's words: "Here's my attempt Adding the modulus is easily done by another case in main and using the fmod function. The standard library has been mentioned at this point so it should be valid t..

Answer to Exercise 4-2, page 73 Solution by Dann Corbit Extend atof to handle scientific notation of the form 123.45e-6 where a floating-point number may be followed by e or E and an optionally signed exponent. /* ** Written by Dann Corbit as K&R 2, Exercise 4-2 (Page 73). ** Keep in mind that this is *JUST* a student exercise, and is ** light years away from being robust. ** ** Actually, it's k..

Answer to Exercise 4-1, page 71 Solution by Rick Dearman Write the function strrindex(s,t) , which returns the position of the rightmost occurrence of t in s , or -1 if there is none. /* Test driver by Richard Heathfield * Solution (strrindex function) by Rick Dearman */ #include /* Write the function strrindex(s,t), which returns the position ** of the rightmost occurrence of t in s, or -1 if t..

Answer to Exercise 3-6, page 64 Solution by Paul Griffiths Write a version of itoa that accepts three arguments instead of two. The third argument is a minimum field width; the converted number must be padded with blanks on the left if necessary to make it wide enough. /* EX3_6.C ======= Suggested solution to Exercise 3-6 */ #include #include void itoa(int n, char s[], int width); void reverse(c..