Script started on Mon Oct 14 12:29:20 2024
mweeks@air:C_ch11$ echo code for today:  2112
code for today: 2112
mweeks@air:C_ch11$ cat indirection.c 
/* 
  indirection -- don't do this without assigning value first
*/
#include <stdio.h>

int main (void) {

  int *p;
  printf("%d", *p);

  printf("\n");

  return 0;
}


mweeks@air:C_ch11$ cat ptr_assign1.c 
/* 
  ptr_assign1.c
*/
#include <stdio.h>

int main (void) {

  int i=1, j=2, *p, *q;
  p = &i;
  q = p;

  *p = 5;  // (Same as i = 5)

  printf("p points to %d\n", *p);
  printf("q points to %d\n", *q);

  return 0;
}


mweeks@air:C_ch11$ gcc ptr_assign1.c 
mweeks@air:C_ch11$ ./a.ut
bash: ./a.ut: No such file or directory
mweeks@air:C_ch11$ ./a.out
p points to 5
q points to 5
mweeks@air:C_ch11$ cat pointer2a.c 
/* 
  indirection -- don't do this without assigning value first
*/
#include <stdio.h>

int main (void) {

  int a = 3;
  int *p;
  p = &a;

  printf("p = %d\n", *p);
  (*p)++;
  printf("p = %d\n", *p);
  printf("a = %d\n", a);

  printf("\n");

  return 0;
}


mweeks@air:C_ch11$ gcc pointer2a.c
mweeks@air:C_ch11$ ./a.out
p = 3
p = 4
a = 4

mweeks@air:C_ch11$ cat pointer2a_v2.c 
/* 
  indirection -- don't do this without assigning value first
*/
#include <stdio.h>

int main (void) {

  int a = 3;
  int *p;
  p = &a;

  printf("p = %d\n", *p);
  (p++);
  printf("p = %d\n", *p);
  printf("a = %d\n", a);

  printf("\n");

  return 0;
}


mweeks@air:C_ch11$ gcc pointer2a_v2.c 
mweeks@air:C_ch11$ ./a.out
p = 3
p = 0
a = 3

mweeks@air:C_ch11$ cat ptr_as_arg.c 
/* 
  ptr_as_arg.c
*/
#include <stdio.h>

void swap (int *p, int *q){
  int temp=0;
  temp = *p;
  *p = *q;
  *q = temp;
}

int main (void) {

  int x = 1, y = 2;
  swap(&x, &y);
  printf("x= %d , y= %d",x,y);
  printf("\n");

  return 0;
}



mweeks@air:C_ch11$ gcc ptr_as_arg.c
mweeks@air:C_ch11$ ./a.out
x= 2 , y= 1
mweeks@air:C_ch11$ cat ptr_as_ret.c 
/* 
  ptr_as_ret.c

  See ch11 of Dr.King's book
*/
#include <stdio.h>

int *max(int *a, int *b) {
  if(*a > *b)
    return a;
  else
    return b;
}

int main (void) {

  int *p, x, y;
  p = max(&x, &y);
  printf("%d\n", *p);

  return 0;
}


mweeks@air:C_ch11$ vi ptr_as_ret.c
mweeks@air:C_ch11$ cat ptr_as_ret.c 
/* 
  ptr_as_ret.c

  See ch11 of Dr.King's book
*/
#include <stdio.h>

int *max(int *a, int *b) {
  if(*a > *b)
    return a;
  else
    return b;
}

int main (void) {

  int *p, x=3, y=5;
  p = max(&x, &y);
  printf("%d\n", *p);

  return 0;
}


mweeks@air:C_ch11$ gcc ptr_as_ret.c
mweeks@air:C_ch11$ ./a.out
5
mweeks@air:C_ch11$ exit
exit

Script done on Mon Oct 14 14:02:29 2024