I have to generate random 100 integers from an array belonging to the interval [0 .. 132] and i have to output those which do not belong to the interval (26 .. 100]

I don't know how to output those which do not belong to the interval. I hope someone can give me some guidance. I'm struggling to find information on internet

My first part of the code is:

            Random rand = new Random();
            for (int i=1; i <=100; i  )
            {
                int x = rand.Next(0, 132);
            }

CodePudding user response：

Instead of generating random numbers which you don't use, generate the ones you need directly:

Random rand = new Random();
for (int i=1; i <=100; i  )
{
    int x = rand.Next(0, 26-0   132-101);
    if (x>26) x =101-26;
}

If the ranges get more complicated, you could use LINQ to construct a concatentation of ranges and take a random from there:

Random rand = new Random(); 
var nums = Enumerable.Range(0,27).Concat(Enumerable.Range(101,32));
for (int i=1; i <=100; i  )     
{
    int x = nums.Skip(rand.Next(0,nums.Count())).First();
}

Don't do that for large ranges. According to @Dmitry Bychenko it can become very slow.

You can also use an if statement as suggested in many comments. But then you need to count the valid numbers and use a while loop instead of a for loop:

Random rand = new Random();
var count = 0;
while (count < 100)
{
    int x = rand.Next(0, 132);
    if (x <= 26 || x > 100)
    {
        count  ;
    }
}

CodePudding user response：

Method 1. Using if selection statement

Just check that x value is more than 100 OR value is less than 27:

if (x < 27 || x > 100)
{
    Console.WriteLine(x);
}

Method 2. Using Enumerable.Range LINQ method

Generate range and check that x value does NOT include in specified range:

if (!Enumerable.Range(27, 100).Contains(x))
{
    Console.WriteLine(x);
}

WARNING: Using this method with large range can have a significant impact on increasing the execution time.