chapter 7

K & R C Programs Exercise 7-7.

Posted on by Sandeepa Nadahalli
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 .

/***********************************************************
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* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
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* 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.

Posted on by Sandeepa Nadahalli
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 .

/***********************************************************
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* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* 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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K & R C Programs Exercise 7-5.

Posted on by Sandeepa Nadahalli
K and R C, Solution to Exercise 7-5:
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.
Rewrite the postfix calculator of chapter 4 to use scanf and/or sscanf to do the input number conversion.
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 [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/



#include<stdio.h>
#include<math.h>       /*for atof()*/
#define MAXTOP 100     /* max size of operand or operator  */
#define NUMBER  '0'    /* SIGNAL THAT A NUMBER WAS FOUND   */
#define MAXVAL 100
int gettop(char []);
void push(double);
double pop(void);
int sp = 0;          /* Next free stack position. */
double val[MAXVAL];  


//reverse Polish calulator
int main(void)
{
 int type;
 double op2;
 char s[MAXOP];

 while((type = getop(s)) != EOF)
 {
  switch(type)
  {
  case NUMBER:
   push(atof(s));
   break;
  case '+':
   push(pop() + pop());
   break;
  case '*':
   push(pop() * pop());
   break;

  case '-':
   op2=pop();
   push(pop() - op2);
   break;
  case '-':
   op2=pop();
   if(op2 != 0.0)
    push(pop() / op2);
   else printf("nError: Zero divissorn");
   break;
  case '%':
   op2 = pop();
   if(op2)
    push(fmod(pop(), op2));
   else
    printf("nError: Division by zero!");
   break;
  case 'n':
   printf("t%.8gn",pop());
   break; 
  default:
   printf("error: unknown command %sn", s);
   break;

  }
 }
 return 0;
}




/* Getop: get next operator or numeric operand. */
int getop(char s[])
{

 int i = 0;
 int c;
 int rc;
 static char lastc[] = " ";
 sscanf(lastc,"%c", &c);
 lastc[0] = ' ';

 /* Skip whitespace */
 while((s[0] = c ) == ' ' || c == 't')
  if(scanf("%",&c) == EOF)
   c = EOF;
 s[1] = '';

 /* Not a number but may contain a unary minus. */
 if(!isdigit(c) && c != '.' )
  return c;               


 if(isdigit(c))
  do{
   rc = scanf("%c",&c);
   if(!isdigit(s[++i] = c))
    break;
  }while(rc != EOF)

   if(c == '.')
    do{
     rc = scanf("%c",&c);
     if(!isdigit(s[++i] = c))
      break;
    }while(rc != EOF)

     s[i] = '';
 if(rc != EOF)
  lastc[0] = c;
 return NUMBER;

}



/* push: push f onto stack. */
void push(double f)
{
 if(sp < MAXVAL)
  val[sp++] = f;
 else
  printf("nError: stack full can't push %gn", f);
}

/*pop: pop and return top value from stack.*/
double pop(void)
{
 if(sp > 0)
  return val[--sp];
 else
 {
  printf("nError: stack emptyn");
  return 0.0;
 }
}

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K & R C Programs Exercise 7-4.

Posted on by Sandeepa Nadahalli
K and R C, Solution to Exercise 7-4:
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 private version of scanf analogous to minprintf from the previous section.
minscanf is similar to minprintf. This function collects characters from the format string until it finds an alphabetic character after a %. That is the localfmt passsed to scanf along with the appropriate pointer.
The arguments to scanf are pointers: a pointer to a format string and a pointer to the variable that receives the value from scanf.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 [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/

#include <stdarg.h>
#include <stdio.h>
#include <ctype.h>
#define LOCALFMT 100

/* minscanf:  minimal scanf with variable argument list */
void minscanf(char *fmt, ...)
{
 va_list ap;
 char *p, *sval;
 char localfmt[LOCALFMT];
 int i,c;
 int *ival;
 double *dval;
 unsigned *uval;

 va_start(ap, fmt);    /* make ap point to the first unnamed arg */
 for (p = fmt; *p; p++) {
  if (*p != '%') {
   localfmt[i++] = *p;
   continue;
  }
  i = 0;
  localfmt[i++] = '%';
  while(*p(p+1) && !isalpha(*(p+1)))
   localfmt[i++] = *++p;
  localfmt[i++] = *(p+1);
  localfmt[i] = '/0';
  switch (*++p) {
  case 'd':
  case 'i':
   ival = va_arg(ap, int *);
   scanf(localfmt, ival);
   break;

  case 'u':

  case 'o':

  case 'x':

  case 'X':


  case 'f':
   dval = va_arg(ap, double);
   scanf(localfmt, dval);
   break;

  case 's':
   sval = va_arg(ap, char *);
   scanf(localfmt, sval);
   break;
  default:
   scanf(localfmt);
   break;
  }
  i = 0;
 }
 va_end(ap);
}


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K & R C Programs Exercise 7-3.

Posted on by Sandeepa Nadahalli
K and R C, Solution to Exercise 7-3:
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 Revise minprintf to handle more of the other facilities of printf. minprintf walks along the argument list and printf does the actual printing for the facilities supported.
To handle more of the other facilities of printf we collect in local fmt the % and any other characters until an alphabetic character -the format letter.local fmt is the format argument for printf. 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 [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/


#include <stdarg.h>
#include <stdio.h>
#include<ctype.h>
#define LOCALFMT 100

/* minprintf:  minimal printf with variable argument list */
void minprintf(char *fmt, ...)
{
 va_list ap;
 char *p, *sval;
 char localfmt[LOCALFMT];
 int i;
 int ival;
 double dval;
 unsigned uval;

 va_start(ap, fmt);    /* make ap point to the first unnamed arg */
 for (p = fmt; *p; p++) {
  if (*p != '%') {
   putchar(*p);
   continue;
  }
  i = 0;
  localfmt[i++] = '%';
  while(*p(p+1) && !isalpha(*(p+1)))
   localfmt[i++] = *++p;
  localfmt[i++] = *(p+1);
  localfmt[i] = '/0';
  switch (*++p) {
  case 'd':
  case 'i':
   ival = va_arg(ap, int);
   printf("%d", ival);
   break;
  case 'c':
   ival = va_arg(ap, int);
   putchar(ival);
   break;
  case 'u':
   uval = va_arg(ap, unsigned int);
   printf("%u", uval);
   break;
  case 'o':
   uval = va_arg(ap, unsigned int);
   printf("%o", uval);
   break;
  case 'x':
   uval = va_arg(ap, unsigned int);
   printf("%x", uval);
   break;
  case 'X':
   uval = va_arg(ap, unsigned int);
   printf("%X", uval);
   break;
  case 'e':
   dval = va_arg(ap, double);
   printf("%e", dval);
   break;
  case 'f':
   dval = va_arg(ap, double);
   printf("%f", dval);
   break;
  case 'g':
   dval = va_arg(ap, double);
   printf("%g", dval);
   break;
  case 's':
   for (sval = va_arg(ap, char *); *sval; sval++)
    putchar(*sval);
   break;
  default:
   putchar(*p);
   break;
  }
 }
 va_end(ap);
}




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K & R C Programs Exercise 7-1.

Posted on by Sandeepa Nadahalli
K and R C, Solution to Exercise 7-1:
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 that converts upper case to lower case or lower case to upper, depending on the name it is invoked with, as found in argv[0]. 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 [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/


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

//lower: converts upper case to lower case
//upper:converts upper case to lower case

main(int argc, *argv[])
{
 int c;
 if(strcmp(argv[0],"lower") == 0)
  while((c = getchar()) != EOF)
   putchar(tolower(c)) != EOF)
   else
    while(c = getchar()) != EOF)
    putchar(toupper(c));
    return 0;
}

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