Obtaining a random object with loops

Lets see if I can phrase this understandably (is that a word?)...

I have an array of class objects. I want to run through the entire array and choose a random one with a special attribute. I don't think I can explain it with english... must use second language, c++

Code:

class Obj{
    int Number;
    int ID;
};

Obj listOfObj[3]

// Pretend I just set the first 2 of the "listOfObj".Number to 1
// and the third's Number to 0.
// and I set each of their ID to their index in the array
// listOfObj[1].ID = 1 etc...

/*Now I want to collect all of the listOfObj's whose "Number" is equal to 1, and randomly choose one of them*/

//I do not have a clue about how to go about this

I hope I worded this good enough. Its a difficult question to put into words. Thanks for the help!

Loop through them all with a for loop. if (Number == 1), increment the total count of acceptable matches, as well as recording the element your at in a lookup table of some sort. An array with size equal to the maximum number of elements scanned through maybe? Using that example do this afterwards:

UseThisOne( LookupArray[rand() % Total_Matches] );

Make sure to check if Total_Matches is > 0 though...

Thats exactly what I tried but it gave me a "Program has encoutered an error", the XP version of illegal operation. Maybe I just did something stupid, I'll try it again. Thanks for the help though.