The document provides an introduction to computer programming pointers in 3 sections. Section 1 defines pointers and their uses to reference memory locations. Section 2 demonstrates how to use pointers to reference and modify variable values. Section 3 shows pointers being used to swap the values of two variables by passing their addresses to a function. The document concludes by thanking the reader.

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4. -3-
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int x,*ix;
void main()
{
clrscr();
x = 123;
printf(x = %dn,x);
ix = x; /* ix point to x variable */
printf(ix = %pn,ix); /* ix value */
printf(x = %dn,*ix);
*ix = *ix + 1;
(*ix)++;
printf(x = %dn,x);
}
x = 123
ix = 045
x = 123
x = 125

5. -4-
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#include stdio.h
void swap(int *ia , int *ib);
void main()
{
int a,b;
a = 123;
b = 456;
clrscr();
printf(a = %d , b = %dn,a,b);
swap(a,b);
printf(a = %d , b = %dn,a,b);
}
void swap(int *ia , int *ib)
{
int tmp;
tmp = *ia;
*ia = *ib;
*ib = tmp;
}
a = 123 , b = 45
a = 456 , b = 12

6. -5-
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#define SIZE 16
#include stdio.h
char a[SIZE] = Hello World.;
char *ia;
int x;
void main()
{
clrscr();
printf(%sn , a);
ia = a;
printf(%sn , ia);
ia[6] = 'w';
printf(%sn , ia);
*(ia+8) = 'R';
printf(%sn , ia);
printf(%c%c%cn , ia[6] , ia[7] , ia[8]);
for(x = 0; ia[x] != 0; x++)
{
printf(%c , ia[strlen(a) - x - 1]);
delay(65535);
delay(65535);
}
printf(nName = );
scanf(%s,ia);
printf(Hello %s,ia);
getch();
}
Hello World.
Hello World.
Hello world.
Hello woRld.
woR
.dlRow olleH
Name = abcd
Hello abcd

7. -6-
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#include stdio.h
#include conio.h
char *ia[2];
char a[16] = Chiangmai;
char b[16] = Thailand;
int x;
void main()
{
clrscr();
printf(%s %sn, a , b);
ia[0] = a;
ia[1] = b;
printf(%s %sn, ia[1] , ia[0]);
textcolor(LIGHTGREEN);
printf(%s %sn, ia[0] , ia[1] + 4);
getch();
}
Chiangmai Thailand
Thailand Chiangmai
Chiangmai land

8. -7-
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#include stdio.h
void main()
{
int **p1;
int *p2, x;
clrscr();
x = 123;
printf(x = %dn , x);
p2 = x;
p1 = p2;
**p1 = *p2 + 2;
printf(x = %dn, **p1);
getch();
}
x = 123
x = 125

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