K & R C Exercise Solutions.

We have already provided solutions to all the exercises in the bookC Programming Language (2nd Edition) popularly known as K & R C book.

In this blog post I will give links to all the chapters of the “C Programming Language (2nd Edition)” popularly known as K & R C book for easy reference.

  1. Chapter 1: A Tutorial Introduction
  2. Chapter 2: Types, Operators and Expressions
  3. Chapter 3: Control Flow
  4. Chapter 4: Functions and Program Structure
  5. Chapter 5: Pointers and Arrays
  6. Chapter 6: Structures
  7. Chapter 7: Input and Output
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K & R C Chapter 7 Exercise Solutions.

We have already provided solutions to all the exercises in the bookC 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 7 of the book for easy reference.

Chapter 7: Input and Output

  1. Exercise 7-1. Write a program that converts upper case to lower or lower case to upper, depending on the name it is invoked with, as found in argv[0].
    Solution to Exercise 7-1.
  2. Exercise 7-2.Write a program that will print arbitrary input in a sensible way. As a minimum, it should print non-graphic characters in octal or hexadecimal according to local custom, and break long text lines.
    Solution to Exercise 7-2.
  3. Exercise 7-3.Revise minprintf to handle more of the facilities of printf .
    Solution to Exercise 7-3.
  4. Exercise 7-4. Write a private version of scanf analogous to minprintf from the previous section.
    Solution to Exercise 7-4.
  5. Exercise 7-5. Rewrite the postfix calculator of Chapter 4 to use scanf and/or sscanf to do the input and number conversion.
    Solution to Exercise 7-5.
  6. Exercise 7-6. Write a program to compare two files, printing the first line where they differ.
    Solution to Exercise 7-6.
  7. Exercise 7-7. Modify the pattern finding program of Chapter 5 to take its input from a set of named files or, if no files are named as arguments, from the standard input. Should the file name be printed when a matching line is found?
    Solution to Exercise 7-7.
  8. Exercise 7-8. Write a program to print a set of files, starting each new one on a new page, with a title and a running page count for each file.
    Solution to Exercise 7-8.
  9. Exercise 7-9. Functions like isupper can be implemented to save space or to save time. Explore both possibilities.
    Solution to Exercise 7-9.
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K & R C Chapter 6 Exercise Solutions.

We have already provided solutions to all the exercises in the bookC 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 6 of the book for easy reference.

Chapter 6: Structures

  1. Exercise 6-1. Our version of getword does not properly handle underscores, string constants, comments, or preprocessor control lines. Write a better version.
    Solution to Exercise 6-1.
  2. Exercise 6-2.Write a program that reads a C program and prints in alphabetical order each group of variable names that are identical in the first 6 characters but different somewhere thereafter. Don’t count words within strings and comments. Make 6 a parameter that can be set from the command line.
    Solution to Exercise 6-2.
  3. Exercise 6-3.Write a cross-referencer that prints a list of all words in a document, and, for each word, a list of the line numbers on which it occurs. Remove noise words like “the,” “and,” and so on.
    Solution to Exercise 6-3.
  4. Exercise 6-4. Write a program that prints the distinct words in its input sorted into decreasing order of frequency of occurrence. Precede each word by its count.
    Solution to Exercise 6-4.
  5. Exercise 6-5. Write a function undef that will remove a name and definition from the table maintained by lookup and install .
    Solution to Exercise 6-5.
  6. Exercise 6-6. Implement a simple version of the #define processor (i.e., no arguments) suitable for use with C programs, based on the routines of this section. You may also find getch and ungetch helpful.
    Solution to Exercise 6-6.
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K & R C Chapter 5 Exercise Solutions.

We have already provided solutions to all the exercises in the bookC 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

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. Exercise 5-8.There is no error-checking in day_of_year or month_day. Remedy this defect.
    Solution to Exercise 5-8.
  9. Exercise 5-9.Rewrite the routines day_of_year and month_day with pointers instead of indexing.
    Solution to Exercise 5-9.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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.
  18. Exercise 5-18. Make dcl recover from input errors.
    Solution to Exercise 5-18.
  19. Exercise 5-19. Modify undcl so that it does not add redundant parentheses to declarations.
    Solution to Exercise 5-19.
  20. 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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K & R C Chapter 4 Exercise Solutions.

We have already provided solutions to all the exercises in the bookC 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 4 of the book for easy reference.

Chapter 4: Functions and Program Structure
    1. Exercise 4-1. Write the function strrindex(s,t) , which returns the position of the rightmost occurrence of t in s , or -1 if there is none.
      Solution to Exercise 4-1.
    1. Exercise 4-2.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.
      Solution to Exercise 4-2.
    1. Exercise 4-3.Given the basic framework, it’s straightforward to extend the calculator. Add the modulus ( % ) operator and provisions for negative numbers.
      Solution to Exercise 4-3.
    1. Exercise 4-4. 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.
      Solution to Exercise 4-4.
    1. Exercise 4-5. Add access to library functions like sin , exp , and pow . See <math.h> in Appendix B, Section 4.
      Solution to Exercise 4-5.
    1. Exercise 4-6. 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.
      Solution to Exercise 4-6.
    2. Exercise 4-7. 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 ?
      Solution to Exercise 4-7.
    1. Exercise 4-8.Suppose that there will never be more than one character of pushback. Modify getch and ungetch accordingly.
      Solution to Exercise 4-8.
    1. Exercise 4-9.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 to Exercise 4-9.
    1. Exercise 4-10. 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 to Exercise 4-10.
    1. Exercise 4-11. Modify getop so that it doesn’t need to use ungetch. Hint: use an internal static variable.
      Solution to Exercise 4-11.
    1. Exercise 4-12. Adapt the ideas of printd to write a recursive version of itoa ; that is, convert an integer into a string by calling a recursive routine.
      Solution to Exercise 4-12.
    1. Exercise 4-13. Write a recursive version of the function reverse(s) , which reverses the string s in place.
      Solution to Exercise 4-13.
  1. Exercise 4-14. Define a macro swap(t,x,y) that interchanges two arguments of type t . (Block structure will help.)
    Solution to Exercise 4-14.
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K & R C Chapter 3 Exercise Solutions

We have already provided solutions to all the exercises in the bookC 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 3 of the book for easy reference.

Chapter 3: Control Flow

  1. Exercise 3-1. Our binary search makes two tests inside the loop, when one would suffice (at the price of more tests outside). Write a version with only one test inside the loop and measure the difference in run-time.
    Solution to Exercise 3-1.
  2. Exercise 3-2.Write a function escape(s,t) that converts characters like newline and tab into visible escape sequences like n and t as it copies the string t to s . Use a switch . Write a function for the other direction as well, converting escape sequences into the real characters.
    Solution to Exercise 3-2.
  3. Exercise 3-3.Write a function expand(s1,s2) that expands shorthand notations like a-z in the string s1 into the equivalent complete list abc…xyz in s2 . Allow for letters of either case and digits, and be prepared to handle cases like a-b-c and a-z0-9 and -a-z . Arrange that a leading or trailing – is taken literally.
    Solution to Exercise 3-3.
  4. Exercise 3-4.In a two’s complement number representation, our version of itoa does not handle the largest negative number, that is, the value of n equal to -(2 to the power (wordsize – 1)) . Explain why not. Modify it to print that value correctly regardless of the machine on which it runs.
    Solution to Exercise 3-4.
  5. Exercise 3-5. Write the function itob(n,s,b) that converts the integer n into a base b character representation in the string s . In particular, itob(n,s,16) formats n as a hexadecimal integer in s
    Solution to Exercise 3-5.
  6. Exercise 3-6. 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.
    Solution to Exercise 3-6.
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K & R C Programs Exercise 7-9.

K and R C, Solution to Exercise 7-9:
K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
Write a C Functions like isupper() can be implemented to save space or to save time. Explore both possibilities. Read more about C Programming Language .
isupper: return 1 (true) if c is an upper case letter
Normal C function:

int  isupper(char c)
{
if (c >= 'A' && c <= 'Z')
return 1;
else
return 0;
}

This simple code tests the character is upper or lower , If the character within the range of ASCII upper case letters it returns 1, otherwise 0.
To save space or to save time using the macros is the best possibility
C Code:

#define isupper(c)  ((c) > = 'A' && (c) <= 'Z') ? 1:0

Macro version of isupper is more efficient because, there is no overhead of the function call and it uses more space because the macro is expanded in line every time it is invoked.

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K & R C Programs Exercise 7-8.

K and R C, Solution to Exercise 7-8:
K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
C Program to print a set of files, starting each new one on a new page, with a title and running page for each file Read more about C Programming Language .

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<stdlib.h>

#define MAXBOT 3
#define MAXHDR 5
#define MAXLINE 100
#define MAXPAGE 66

/*print: print files - each new one on a new page */
main(int argc, char *argv[])
{

FILE *fp;
void fileprint(FILE *fp, char *fname);

if(argc == 1)
fileprint(stdin," ");
else
if((fp = fopen(*++argv,"r")) == NULL) {
fprintf(stderr,"find:can't open %sn",*argv);
exit(1);
} else {

fileprint(fp, *argv);
fclose(fp);
}
return 0;
}


//fileprint: print file name
void fileprint(FILE *fp, char *fname)
{
int lineno, pageno = 1;
char line[MAXLINE];
int heading(char *fname, int pageno);
lineno = heading(fname, pageno++);
while(fgets(line, MAXLINE, fp) != NULL) {
if(lineno == 1) {
fprintf(stdout,"f");
lineno = heading(fname, pageno++);
}
fputs(line, stdout);
if(++lineno > MAXPAGE - MAXBOT)
lineno = 1;
}
fprintf(stdout,"f");
}

//heading: put heading and enough blank lines
int heading(char *fname, int pageno)
{
int ln = 3;
fprintf(stdout,"nn");
fprintf(stdout,"%s page %dn", fname, pageno);
while(ln++ < MAXHDR)
fprintf(stdout,"n");
return ln;
}
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K & R C Programs Exercise 7-7.

K and R C, Solution to Exercise 7-7:
K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
C program to modify the pattern-finding program of chapter 5(C Programming Language  2nd Edition, page no 117.) to take its input from a set of named files or, if no files are named as arguments, from the standard input. Should the file name be printed when a matching line is found.Read more about C Programming Language .

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

#define MAXLINE 1000

/*print lines that match pattern from 1st argument */
main(int argc, char *argv[])
{
char pattern[MAXLINE];
int c, excpet = 0,number = 0;
FILE *fp;
void fpat(FILE *fp, char *fname, char *pattern, int except, int number);

while(--argc > 0 && (*++argv)[0] == '-')
while(c = *++argv[0])
switch(c) {
case 'x':
except = 1;
break;
case 'n':
number = 1;
break;
default:
printf("find:illigal option %cn",c);
argc = 0;
break;
}
if(argc >= 1)
strcpy(pattern, *argv);
else{
printf("Usage:find[-x] [-n] pattern [file....]n");
exit(1);
}
if(argc == 1)
fpat(stdin,"",pattern,except,number);
else
while(--argc > 0)
if((fp = fopen(*++argv,"r")) == NULL) {
fprintf(stderr,"find:can't open %sn",*argv);
exit(1);
} else {
fpat(fp, *argv, pattern,except,number);
fclose(fp);}
return 0;
}

/*fpat: find pattern*/
void fpat(FILE *fp, char *fname, char *pattern, int except, int number)
{
char line[MAXLINE];
long loneno = 0;

while(fgets(line, MAXLINE, fp) != NULL){
++lineno;
if((strstr(line,pattern) != NULL) !=except) {
if(*fname)
printf("%s -",fname);
if(number)
printf("%ld: ",lineno);
printf("%s",line);
}
}
}



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K & R C Programs Exercise 7-6.

K and R C, Solution to Exercise 7-6:
K and R C Programs Exercises provides the solution to all the exercises in the C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
Write a C Program to compare two files, printing the first line where they differ.
Read more about C Programming Language .

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define MAXLINE 100
/*comp: compare two file, printing the first line where they differ*/
main(int argc, char *argv[])
{
FILE *fp1, *fp2;
void filecomp(FILE *fp1, FILE *fp2);
if(argc != 3){
fprintf(stderr,"comp:need two file namesn");
exit(1);
} else {
if((fp1 = fopen(*++argv, "r")) == NULL) {
fprintf(stderr, "comp:can't open %sn",*argv);
exit(1);
} else if((fp2 = fopen(*++argv, "r")) == NULL) {
fprintf(stderr, "comp:can't open %sn",*argv);
exit(1);
}else {
filecomp(fp1,fp2);
fclose(fp1);
fclose(fp2);
exit(0);

}
}
}

//filecomp: compare two files -a line at a time
void filecomp (FILE *fp1, FILE *fp2)
{
char line1[MAXLINE], line2[MAXLINE];
char *lp1 = *lp2;
do{
lp1 = fgets(line1, MAXLINE, fp1);
lp2 = fgets(line2, MAXLINE, fp2);
if(lp1 == line1 && lp2 == line2){

if(strcmp(line1,line2) !=0) {
printf("First difference in linen%sn",line1);
lp1 = lp2 = NULL;
}
} else if(lp1 != line1 && lp2 == line2)
printf("end of first file at linen%sn",line2);
else if(lp1 == line1 && lp2 == line2)
printf("end of second file at line n%sn",line1);

}while(lp1 == line1 && lp2 == line2);
}



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