Nested for loop to calculate prime number : For « Statement « C# / CSharp Tutorial






  1. C# / CSharp Tutorial
  2. Statement
  3. For
using System; 
 
class MainClass {    
  public static void Main() {    
    int num; 
    int i; 
    int factor; 
    bool isprime; 
 
 
    for(num = 2; num < 20; num++) { 
      isprime = true;  
      factor = 0; 
 
      // see if num is evenly divisible 
      for(i=2; i <= num/2; i++) { 
        if((num % i) == 0) { 
          // num is evenly divisible -- not prime 
          isprime = false; 
          factor = i; 
        } 
      } 
 
      if(isprime) 
        Console.WriteLine(num + " is prime."); 
      else 
        Console.WriteLine("Largest factor of " + num + 
                          " is " + factor); 
    } 
 
  }    
}

2 is prime.
3 is prime.
Largest factor of 4 is 2
5 is prime.
Largest factor of 6 is 3
7 is prime.
Largest factor of 8 is 4
Largest factor of 9 is 3
Largest factor of 10 is 5
11 is prime.
Largest factor of 12 is 6
13 is prime.
Largest factor of 14 is 7
Largest factor of 15 is 5
Largest factor of 16 is 8
17 is prime.
Largest factor of 18 is 9
19 is prime.




4.3.For
4.3.1.for loop
4.3.2.Demonstrate a block of code inside if statement
4.3.3.Use block inside for statement: Compute the sum and product of the numbers from 1 to 10
4.3.4.Use byte to control for loop
4.3.5.A negatively running for loop
4.3.6.Nested for loop to calculate prime number
4.3.7.Use commas in a for statement.
4.3.8.Use commas in a for statement to find the largest and smallest factor of a number
4.3.9.Loop condition can be any bool expression.
4.3.10.Parts of the for can be empty.
4.3.11.Move 'update' out of the for loop
4.3.12.For loop with multiple expressions
4.3.13.The body of a loop can be empty
4.3.14.Declare loop control variable inside the for
4.3.15.Using break to exit a for loop