C Puzzle

[M@rv|n]

---

ayaw ipa run ... predict lang unsa output
naa ra ninyo kng mo cheat mo or dli

=============

Write the output of this program

#include

main()
{
int *a, *s, i;

s = a = (int *) malloc( 4 * sizeof(int));

for (i=0; i<4; i++) *(a+i) = i * 10;

printf("%d\n", *s++);
printf("%d\n", (*s)++);
printf("%d\n", *s);
printf("%d\n", *++s);
printf("%d\n", ++*s);
}

[silent-kill]

actually di ni mo run kai sayop imong #include heeheh sakto?

[red_colt]

ayaw ipa run ... predict lang unsa output
naa ra ninyo kng mo cheat mo or dli

=============

Write the output of this program

#include

main()
{
int *a, *s, i;

s = a = (int *) malloc( 4 * sizeof(int));

for (i=0; i<4; i++) *(a+i) = i * 10;

printf("%d\n", *s++);
printf("%d\n", (*s)++);
printf("%d\n", *s);
printf("%d\n", *++s);
printf("%d\n", ++*s);
}

d mo run kay sayop ang include pero cge try lng gihapon....................liboga oi. kapoy trace. ngano gud imanual ni oi.

[M@rv|n]

ahehe sagdi nalang gud na ang include ... nya aron daghan nata mag kutaw utok bah ... kaila kag ang level ani is easy lang? ahehe unsa nalang kaha ang hard noh?

[gloryhunter]

Sige ko tutok ana nga program, the title is puzzle so i am trying to see where's the catch or trick there. But this is just plain program.

main()
{
int *a, *s, i;

s = a = (int *) malloc( 4 * sizeof(int)); // allocating 4 int bytes; 'a' and 's' vars points for the 1st address of the allocated memory

for (i=0; i<4; i++) *(a+i) = i * 10; // assigning 0, 10, 20, 30 to the address of (a + 1, a + 2 and so on);

printf("%d\n", *s++); // dereferencing or get the value of the first address, the value is=0; increment the address at the same time
// it's the same as (*s) then s = s + 1;
printf("%d\n", (*s)++); //dereference the 2nd address, the value is 10; increment it by 1
// it's the same as (*s) = (*s) + 1;
printf("%d\n", *s); // dereference the 2nd address which was increased 1, the value now is 11
printf("%d\n", *++s); // increments the address then dereference, s = s + 1, s now is pointing the 3rd element, then dereference *s, value is 20
printf("%d\n", ++*s); // deference s (*s), the value of the 3rd element, then increment it by 1, value is 20 + 1=21
}


the output should be 0, 10, 11, 20, 21

Good exercise though.

[M@rv|n]

koyawa gloryhunter oi! ahehe sakto bhay! hmmm murag dli naman tingali na explain kay naa naman explaination c gloryhunter

[M@rv|n]

Next question

Write a program to swap two integers without using 3rd integer (ie. Without using any temporary variable)

[gloryhunter]

using xor swap.

----------
#include <stdio.h>

void swap(int *x, int *y);

main()
{
int x = 10, y = 20;
swap(&x, &y);
printf("%d, %d", x, y);
return 0;
}

void swap(int *x, int *y)
{
*x ^= *y;
*y ^= *x;
*x ^= *y;
}

[M@rv|n]

sakto bhay! ahehe pero ang ako answer is this :d
hilig jud ko ug one liner ahehe
============

int x, y;

printf("enter x y: ");
scanf("%d %d", &x, &y);

x^=y^=x^=y;

printf("%d, %d",x, y);

[gloryhunter]

one liner is fine but i wont do it if compromise readability.