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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 by Gregory Pietsch /* Gregory Pietsch ex. 5-6 dated 2001-01-29 */ #include #include #include /* getline: get line ..

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 by Lars Wirzenius Note: Lars uses EXIT_FAILURE in his test code, but not in the actual solution code. As far as I can tell, then, this ..

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 by Bryan Williams /* 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. Author : Bryan Williams */ int strlen(char *s) /* added by RJH; source: K&R p99 */ { int n; for(n = 0; *s != '\0';..

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 by Richard Heathfield /* ex 5-3, p107 */ #include void strcpy(char *s, char *t) { while(*s++ = *t++); } void strcat(char *s, char *t) { while(*s) { ++s; } strcpy(s, t); } int main(void) { char testbuff[128]; char *test[] = { "", "1", "12", "123", "1234" }; size_t..

Write getfloat , the floating-point analog of getint . What type does getfloat return as its function value? Solutions by Chris Mears and Gregory Pietsch Here is Chris's solution: /* * Exercise 5-2 from The C Programming Language, 2nd edition, by Kernighan * and Ritchie. * * "Write getfloat, the floating-point analog of getint. What type does * getfloat return as its function value?" */ /* * Her..

Answer to Exercise 4-14, page 91 Solutions by Gregory Pietsch and Lars Wirzenius Define a macro swap(t,x,y) that interchanges two arguments of type t . (Block structure will help.) Here are Greg's solutions for Cat 0 and Cat 1: /* EXERCISE 4-14 Gregory Pietsch */ /* conditional compilation added by RJH */ #ifdef CATEGORY_0 #define swap(t,x,y) do{t z=x;x=y;y=z}while(0) #else #ifdef CATEGORY_1 /* ..

Answer to Exercise 4-13, page 88 Solution by Gregory Pietsch Write a recursive version of the function reverse(s) , which reverses the string s in place. /* EXERCISE 4-13 Gregory Pietsch */ static void swap(char *a, char *b, size_t n) { while (n--) { *a ^= *b; *b ^= *a; *a ^= *b; a++; b++; } } void my_memrev(char *s, size_t n) { switch (n) { case 0: case 1: break; case 2: case 3: swap(s, s + n -..

Answer to Exercise 4-12, page 88 Solution by Gregory Pietsch Adapt the ideas of printd to write a recursive version of atoi ; that is, convert an integer into a string by calling a recursive routine. /* itoa() is non-standard, but defined on p.64 as having this prototype: void itoa(int n, char s[]) Instead of this, I thought I'd use a different prototype (one I got from the library manual of one..

Modify getop so that it doesn't need to use ungetch. Hint: use an internal static variable. Solution by Gregory Pietsch, and Liangming #include #define NUMBER '0' int getop(char *s) { int c; static int buf = EOF; if (buf != EOF && buf != ' ' && buf != '\t' && !isdigit(buf) && buf != '.') { c = buf; buf = EOF; return c; } if (buf == EOF || buf == ' ' || buf == '\t') while ((*s = c = getch()) == '..

An alternate organization uses getline to read an entire input line; this makes getch and ungetch unnecessary. Revise the calculator to use this approach. An alternate organization uses getline to read an entire input line; this makes getch and ungetch unnecessary. Revise the calculator to use this approach. Solution by Franz Fritsche. /* K&R Exercise 4-10 */ /* Franz Fritsche */ #include #inclu..