How to generate the first 100 even Numbers using C#?

To generate the first 100 even numbers in C#, you can use a for loop and check if each number is divisible by 2. An even number has no remainder when divided by 2, which can be tested using the modulo operator (%).

What are Even Numbers?

Even numbers are integers that are divisible by 2 without a remainder. Examples include 2, 4, 6, 8, 10, and so on. The condition number % 2 == 0 identifies even numbers.

Using a For Loop with Modulo Check

The most straightforward approach is to iterate through numbers 1 to 100 and check each number for evenness −

using System;

class Program {
   static void Main() {
      int val;
      Console.WriteLine("First 100 even numbers:");
      for(val = 1; val <= 100; val++) {
         if(val % 2 == 0) {
            Console.WriteLine(val);
         }
      }
   }
}

The output of the above code is −

First 100 even numbers:
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
82
84
86
88
90
92
94
96
98
100

Using Direct Even Number Generation

A more efficient approach is to generate even numbers directly by starting with 2 and incrementing by 2 each time −

using System;

class Program {
   static void Main() {
      Console.WriteLine("First 100 even numbers (optimized):");
      for(int i = 2; i <= 200; i += 2) {
         Console.WriteLine(i);
      }
   }
}

The output of the above code is −

First 100 even numbers (optimized):
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
82
84
86
88
90
92
94
96
98
100
102
104
106
108
110
112
114
116
118
120
122
124
126
128
130
132
134
136
138
140
142
144
146
148
150
152
154
156
158
160
162
164
166
168
170
172
174
176
178
180
182
184
186
188
190
192
194
196
198
200

Using Counter-Based Approach

Another method uses a counter to generate exactly 100 even numbers regardless of their actual values −

using System;

class Program {
   static void Main() {
      int count = 0;
      int number = 2;
      Console.WriteLine("First 100 even numbers (counter-based):");
      
      while(count < 100) {
         Console.WriteLine(number);
         number += 2;
         count++;
      }
   }
}

The output shows the first 100 even numbers starting from 2.

Comparison of Methods

Conclusion

Generating the first 100 even numbers in C# can be accomplished using multiple approaches. The modulo check method is straightforward but less efficient, while direct generation and counter-based approaches provide better performance by avoiding unnecessary checks.