Generating random numbers in Objective-C

Question

I\'m a Java head mainly, and I want a way to generate a pseudo-random number between 0 and 74. In Java I would use the method:

Random.nextInt(74)
         


        

Answer 1

I wrote my own random number utility class just so that I would have something that functioned a bit more like Math.random() in Java. It has just two functions, and it's all made in C.

Header file:

//Random.h
void initRandomSeed(long firstSeed);
float nextRandomFloat();

Implementation file:

//Random.m
static unsigned long seed;

void initRandomSeed(long firstSeed)
{ 
    seed = firstSeed;
}

float nextRandomFloat()
{
    return (((seed= 1664525*seed + 1013904223)>>16) / (float)0x10000);
}

It's a pretty classic way of generating pseudo-randoms. In my app delegate I call:

#import "Random.h"

- (void)applicationDidFinishLaunching:(UIApplication *)application
{
    initRandomSeed( (long) [[NSDate date] timeIntervalSince1970] );
    //Do other initialization junk.
}

Then later I just say:

float myRandomNumber = nextRandomFloat() * 74;

Note that this method returns a random number between 0.0f (inclusive) and 1.0f (exclusive).