My loop isn't working and I don't know why.,My loops arent working.

two errors in my short collection of practice loops

(23,25): error CS0029: Cannot implicitly convert type 'int' to 'bool'

(23,31): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement

Here's the entire thing:

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class LoopsChallenge : MonoBehaviour { int num = -5; int j = 10; int k = 1; // Start is called before the first frame update void Start() { while (num <= 5) { print(num);

         num += 1;
     }
     for(int i = -5; i ++; i <= 5)
     {
         print(i);
     }

     while (j <= 50)
     {
         print(j);
         j += 2;
     }
     while(k <= 100) {
         if (k % 5 == 0 && k % 3 == 0)
         {
             print(k);
         }

         k += 1;
     }
 }
 // Update is called once per frame
 void Update()
 {
 }

}