Script started on Wed Oct  9 12:28:50 2024
mweeks@air:C_ch8$ echo 1989
1989
mweeks@air:C_ch8$ ls
Oct9_2024.log		maybe_infinite.c	void_main.c
checkTSize.c		repdigit.c
ident.c			reverse.c
mweeks@air:C_ch8$ cat ident.c
#include <stdio.h>
#define N 10

int main() {
  double ident[N][N];
  int row, col;
  for (row = 0; row < N; row++)
    for (col = 0; col < N; col++)
      if (row == col)
        ident[row][col] = 1.0;
      else
        ident[row][col] = 0.0;

  return 0;
}

mweeks@air:C_ch8$ vi ident.c 
mweeks@air:C_ch8$ gcc ident.c 
ident.c:16:19: warning: invalid conversion specifier ' '
      [-Wformat-invalid-specifier]
      printf("%5.2 ", ident[row][col]);
              ~~~~^
1 warning generated.
mweeks@air:C_ch8$ vi ident.c 
mweeks@air:C_ch8$ gcc ident.c 
mweeks@air:C_ch8$ cat ident.c 
#include <stdio.h>
#define N 10

int main() {
  double ident[N][N];
  int row, col;
  for (row = 0; row < N; row++)
    for (col = 0; col < N; col++)
      if (row == col)
        ident[row][col] = 1.0;
      else
        ident[row][col] = 0.0;

  for (row = 0; row < N; row++) {
    for (col = 0; col < N; col++)
      printf("%5.2f ", ident[row][col]);
    printf("\n");
  }
 
  return 0;
}

mweeks@air:C_ch8$ ./a.out
 1.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00 
 0.00  1.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00 
 0.00  0.00  1.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00 
 0.00  0.00  0.00  1.00  0.00  0.00  0.00  0.00  0.00  0.00 
 0.00  0.00  0.00  0.00  1.00  0.00  0.00  0.00  0.00  0.00 
 0.00  0.00  0.00  0.00  0.00  1.00  0.00  0.00  0.00  0.00 
 0.00  0.00  0.00  0.00  0.00  0.00  1.00  0.00  0.00  0.00 
 0.00  0.00  0.00  0.00  0.00  0.00  0.00  1.00  0.00  0.00 
 0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  1.00  0.00 
 0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  1.00 
mweeks@air:C_ch8$ cat repdigit.c 
/*********************************************************
 * From C PROGRAMMING: A MODERN APPROACH, Second Edition *
 * By K. N. King                                         *
 * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
 * All rights reserved.                                  *
 * This program may be freely distributed for class use, *
 * provided that this copyright notice is retained.      *
 *********************************************************/

/* repdigit.c (Chapter 8, page 166) */
/* Checks numbers for repeated digits */

#include <stdbool.h>   /* C99 only */
#include <stdio.h>

int main(void)
{
  bool digit_seen[10] = {false};
  int digit;
  long n;

  printf("Enter a number: ");
  scanf("%ld", &n);

  while (n > 0) {
    digit = n % 10;
    if (digit_seen[digit])
      break;
    digit_seen[digit] = true;
    n /= 10;
  }

  if (n > 0)
    printf("Repeated digit\n");
  else
    printf("No repeated digit\n");

  return 0;
}
mweeks@air:C_ch8$ 
mweeks@air:C_ch8$ vi repdigit.c 
mweeks@air:C_ch8$ gcc repdigit.c
mweeks@air:C_ch8$ cat repdigit.c
/*********************************************************
 * From C PROGRAMMING: A MODERN APPROACH, Second Edition *
 * By K. N. King                                         *
 * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
 * All rights reserved.                                  *
 * This program may be freely distributed for class use, *
 * provided that this copyright notice is retained.      *
 *********************************************************/

/* repdigit.c (Chapter 8, page 166) */
/* Checks numbers for repeated digits */

#include <stdbool.h>   /* C99 only */
#include <stdio.h>

int main(void)
{
  bool digit_seen[10] = {false};
  int digit;
  long n;

  printf("Enter a number: ");
  scanf("%ld", &n);

  while (n > 0) {
    digit = n % 10;
    if (digit_seen[digit])
      break;
    digit_seen[digit] = true;
    n /= 10;
  }

  if (n > 0)
    printf("Repeated digit\n");
  else
    printf("No repeated digit\n");

  // print y if a digit was seen
  printf("digits seen are:\n");
  for (int i=0; i<10; i++) {
    if (digit_seen[i]) 
      printf("y");
    else
      printf("n");

  }
  printf("\n");

  return 0;
}
mweeks@air:C_ch8$ ./a.out
Enter a number: 123
No repeated digit
digits seen are:
nyyynnnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 1232
Repeated digit
digits seen are:
nnyynnnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 4443
Repeated digit
digits seen are:
nnnyynnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 3221
Repeated digit
digits seen are:
nyynnnnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 321
No repeated digit
digits seen are:
nyyynnnnnn
mweeks@air:C_ch8$ 
mweeks@air:C_ch8$ ls
Oct9_2024.log		ident.c			reverse.c
a.out			maybe_infinite.c	void_main.c
checkTSize.c		repdigit.c
mweeks@air:C_ch8$ cp repdigit.c repdigit2.c
mweeks@air:C_ch8$ vi repdigit2.c
mweeks@air:C_ch8$ gcc repdigit2.c
mweeks@air:C_ch8$ cat repdigit2.c 
/*********************************************************
 * From C PROGRAMMING: A MODERN APPROACH, Second Edition *
 * By K. N. King                                         *
 * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
 * All rights reserved.                                  *
 * This program may be freely distributed for class use, *
 * provided that this copyright notice is retained.      *
 *********************************************************/

/* repdigit.c (Chapter 8, page 166) */
/* Checks numbers for repeated digits */

#include <stdbool.h>   /* C99 only */
#include <stdio.h>

int main(void)
{
  bool digit_seen[10] = {false};
  int digit;
  long n;

  printf("Enter a number: ");
  scanf("%ld", &n);

  //long m = n;
  bool found_repeat = false;

  while (n > 0) {
    digit = n % 10;
    if (digit_seen[digit]) {
      found_repeat = true;
    }
    digit_seen[digit] = true;
    n /= 10;
  }

  if (found_repeat)
    printf("Repeated digit\n");
  else
    printf("No repeated digit\n");

  // print y if a digit was seen
  printf("digits seen are:\n");
  for (int i=0; i<10; i++) {
    if (digit_seen[i]) 
      printf("y");
    else
      printf("n");
  }
  printf("\n");

  return 0;
}
mweeks@air:C_ch8$ ./a.out
Enter a number: 123
No repeated digit
digits seen are:
nyyynnnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 1232
Repeated digit
digits seen are:
nyyynnnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 144442
Repeated digit
digits seen are:
nyynynnnnn
mweeks@air:C_ch8$ ./a.out
Enter a number: 142
No repeated digit
digits seen are:
nyynynnnnn
mweeks@air:C_ch8$ cat reverse.c 
/*********************************************************
 * From C PROGRAMMING: A MODERN APPROACH, Second Edition *
 * By K. N. King                                         *
 * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
 * All rights reserved.                                  *
 * This program may be freely distributed for class use, *
 * provided that this copyright notice is retained.      *
 *********************************************************/

/* reverse.c (Chapter 8, page 164) */
/* Reverses a series of numbers */

#include <stdio.h>

#define N 10

int main(void)
{
  int a[N], i;

  printf("Enter %d numbers: ", N);
  for (i = 0; i < N; i++)
    scanf("%d", &a[i]);

  printf("In reverse order:");
  for (i = N - 1; i >= 0; i--)
    printf(" %d", a[i]);
  printf("\n");

  return 0;
}

mweeks@air:C_ch8$ gcc reverse.c
mweeks@air:C_ch8$ ./a.out
Enter 10 numbers: 1 2 3 4 5 6 7 8 9 10
In reverse order: 10 9 8 7 6 5 4 3 2 1
mweeks@air:C_ch8$ cd ../C_ch9
mweeks@air:C_ch9$ cat average_declaration.c 
/* 
  Example Function Declaration 1:
    fn must be defined before the call
*/

#include <stdio.h>

double average(double a, double b) { 
  return (a + b)/2; 
}   
        
int main() {     
  // ...
  double x=1.0, y=3.0;
  average(x, y);  
 
  return 0;
}
mweeks@air:C_ch9$ vi average_declaration.c
mweeks@air:C_ch9$ gcc average_declaration.c
mweeks@air:C_ch9$ cat average_declaration.c
/* 
  Example Function Declaration 1:
    fn must be defined before the call
*/

#include <stdio.h>

double average(double a, double b) { 
  return (a + b)/2; 
}   
        
int main() {     
  // ...
  double x=1.0, y=3.0;
  double avg;
  //average(x, y);  
  avg = average(x, y);  
  printf("x is %f and y is %f and the avg is %f\n", x, y, avg);
  return 0;
}
mweeks@air:C_ch9$ ./a.out
x is 1.000000 and y is 3.000000 and the avg is 2.000000
mweeks@air:C_ch9$ cp average_declaration.c average_declaration_v2.c
mweeks@air:C_ch9$ vi average_declaration_v2.c 
mweeks@air:C_ch9$ gcc average_declaration_v2.c 
mweeks@air:C_ch9$ cat average_declaration_v2.c
/* 
  Example Function Declaration 1:
    fn must be defined before the call
*/

#include <stdio.h>

double average(double a, double b) { 
  double f = a;
  a = 5.0; // changing a does not change x
  return (f + b)/2; 
}   
        
int main() {     
  // ...
  double x=1.0, y=3.0;
  double avg;
  //average(x, y);  
  avg = average(x, y);  
  printf("x is %f and y is %f and the avg is %f\n", x, y, avg);
  return 0;
}
mweeks@air:C_ch9$ ./a.out
x is 1.000000 and y is 3.000000 and the avg is 2.000000
mweeks@air:C_ch9$ cp average_declaration_v2.c average_declaration_v3.c
mweeks@air:C_ch9$ vi average_declaration_v3.c 
mweeks@air:C_ch9$ gcc average_declaration_v3.c 
mweeks@air:C_ch9$ cat average_declaration_v3.c 
/* 
  Example Function Declaration 1:
    fn must be defined before the call
*/

#include <stdio.h>

double average(double *a, double b) { 
  double f = *a;
  *a = 5.0; // changing a does change x
  return (f + b)/2; 
}   
        
int main() {     
  // ...
  double x=1.0, y=3.0;
  double avg;
  //average(x, y);  
  avg = average(&x, y);  
  printf("x is %f and y is %f and the avg is %f\n", x, y, avg);
  return 0;
}
mweeks@air:C_ch9$ ./a.out
x is 5.000000 and y is 3.000000 and the avg is 2.000000
mweeks@air:C_ch9$ vi memory.txt
mweeks@air:C_ch9$ cat memory.txt 

memory
           byte values
(hex)      (dec)
address    value
0000       23
0001       34
0002       17
0003       9
...
0201       0        x is here
0202       125        extends to next byte
0203       125        extends to next byte
0204       101        extends to next byte
0205       1          extends to next byte
0206       101        extends to next byte
0207       1          extends to next byte
0208       125        extends to next byte
0209       101      y is here
020A       1          extends to next byte
020B       4
...
FFFF       54

mweeks@air:C_ch9$ ls av*
average_declaration.c		average_declaration_v2.c
average_declaration2.c		average_declaration_v3.c
mweeks@air:C_ch9$ cat average_declaration2.c 
/* 
  Example Function Declaration 2:
    fn declared; can now go after the call
*/

#include <stdio.h>

double average(double x, double y); 
        
int main() {     
  // ...
  average(x, y);  
 
  return 0;
}

double average(double x, double y) { 
  // ...
}   
mweeks@air:C_ch9$ ls
a.out				memory.txt
average_declaration.c		myexit.c
average_declaration2.c		power.c
average_declaration_v2.c	power2.c
average_declaration_v3.c	prime.c
fact.c				qsort.c
mweeks@air:C_ch9$ cat myexit.c
#include <stdio.h>
#include <stdlib.h> /* needed for exit */

int main() {
  printf("I am going to exit with status code 42\n");
  exit(42);
}
mweeks@air:C_ch9$ gcc myexit.c
mweeks@air:C_ch9$ ./a.out
I am going to exit with status code 42
mweeks@air:C_ch9$ cat power.c
/* 
  Args vs Params   
  See Dr. King's book, chapter 9
*/

#include <stdio.h>

int power(int x, int n) {
  int i, result = 1;
  for (i = 1; i <= n; i++)
    result = result * x;
  return result;
}

int main (int argc, char *argv[]) {

   
   printf("power(2,3) returns %d.\n", power(2,3)); 

   return 0;
}
mweeks@air:C_ch9$ gcc power.c
mweeks@air:C_ch9$ ./a.out
power(2,3) returns 8.
mweeks@air:C_ch9$ ls
a.out				memory.txt
average_declaration.c		myexit.c
average_declaration2.c		power.c
average_declaration_v2.c	power2.c
average_declaration_v3.c	prime.c
fact.c				qsort.c
mweeks@air:C_ch9$ more power2.c
/* 
  Args vs Params   
  See Dr. King's book, chapter 9
*/

#include <stdio.h>

// Alternate form
int power(int x, int n) {
  int result = 1;
  // n is a *copy* 
  while (n-- > 0) 
    result = result * x;
  return result;
}

int main (int argc, char *argv[]) {

   
   printf("power(2,3) returns %d.\n", power(2,3)); 

   return 0;
}
mweeks@air:C_ch9$ gcc power2.c
mweeks@air:C_ch9$ ./a.out
power(2,3) returns 8.
mweeks@air:C_ch9$ vi short_circuit.txt
mweeks@air:C_ch9$ cat short_circuit.txt 

||  or  &&

these are done in a short-circuit way

bool raining = true;

if (raining || (have_umbrella))
  printf("it is wet outside\n");

if (!raining && (walking))
  printf("take umbrella\n");

mweeks@air:C_ch9$ exit
exit

Script done on Wed Oct  9 13:44:53 2024