Member Avatar for prashanth s j

Hi all,

please anybody help me in solving the following questions:
1)What is a NULL Macro? What is the difference between a NULL Pointer and a NULL Macro?

2)What is the difference between the functions rand(), random(), srand() and randomize()?

Regards,
Prashanth

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  • Latest Post Latest Post by Tom Gunn
Member Avatar for Tom Gunn

1)What is a NULL Macro? What is the difference between a NULL Pointer and a NULL Macro?

The NULL macro is a symbolic name for a null pointer constant. It is defined something like this:

#define NULL ((void*)0)

or this:

#define NULL 0

2)What is the difference between the functions rand(), random(), srand() and randomize()?

rand() returns a pseudo random number between 0 and RAND_MAX. srand() seeds the random number generator that rand() uses so that the same sequence is not generated each time. Under the hood rand() and srand() work something like this:

static int __seed;

void srand(int seed)
{
    __seed = seed;
}

int rand()
{
    int r = {cool math using __seed};

    ++__seed;

    return r;
}

random() and randomize() are not part of the C library, but if a compiler supports them they probably work similarly to rand() and srand().

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