arc4random problem (simple)

[mcsilvio]

Hi guys,
I'm having trouble properly using this.

if i need a somewhat random number between 0 and 4 i thought i need to call

int newValue = arc4random() % 5

to get around this i tried making newValue unsigned. but that didnt help. I get numbers much higher than what the modulus is.

but when i test this in the debugger i get negative values too. any ideas?

i dont need good randomness, the basic stuff will be fine.

thanks guys,
marco.

[kalx]

Originally Posted by mcsilvio

Hi guys,
I'm having trouble properly using this.

if i need a somewhat random number between 0 and 4 i thought i need to call

int newValue = arc4random() % 5

to get around this i tried making newValue unsigned. but that didnt help. I get numbers much higher than what the modulus is.

but when i test this in the debugger i get negative values too. any ideas?

i dont need good randomness, the basic stuff will be fine.

thanks guys,
marco.

That statement looks fine. Are you using NSLog to display the value in the debugger? Can you paste the NSLog code line? Also, are you sure you're not modifying the value anywhere between the assignment and the NSLog? Try putting the NSLog right after the assignment statement.

- kalx

[Gamer211]

I don't mean to sound like a jerk, but did you google "arc4random code for iphone", when I did I got a few explainations. Some from this site.

[mcsilvio]

Originally Posted by Gamer211

I don't mean to sound like a jerk, but did you google "arc4random code for iphone", when I did I got a few explainations. Some from this site.

yes i did. its such a simple statement thats why i dont understand what im doing wrong.

a few more notes.

in gdb im using "print" to see the value in the variable.

second, this is what my line of code looks like exactly

int newValue = arc4random() % [self.myArray count];

and to test i am just typing this in gdb

print (int)arc4random() % [myArray count]

note: there is a casting problem in gdb so that line might not be exact.

any more ideas guys?

[kalx]

Doing something like "print (unsigned int)arc4random() % 5" in GDB works fine for me. I doubt arc4random() is the problem, it probably has something to do with the value of [self.myArray count].

Try this:

int newValue = arc4random() % 5;
NSLog(@"Random Mod 5 Value: %d", newValue);

newValue = arc4random() % [self.myArray count];
NSLog(@"Randomly Generated Value: %d with Array Count: %d", newValue, [self.myArray count]);

then run your application in simulator and see what gets output in the debugger console. The first NSLog statement should work fine. For the second one, I'm betting that the value you see for Array Count is incorrect/garbage.

- kalx