Continue statement behavior in C Sharp (C#) - Time & Space Complexity

Time Complexity: Continue statement behavior

O(n)

Understanding Time Complexity

Let's see how the continue statement affects the time it takes for a loop to run.

We want to know how skipping some steps changes the total work done.

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

for (int i = 0; i < n; i++)
{
    if (i % 2 == 0)
        continue;
    // Some constant time work here
    Console.WriteLine(i);
}
    

This code loops from 0 to n-1 but skips the loop body when the number is even.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The loop runs from 0 to n-1.
• How many times: The loop runs n times, but the body runs only for odd numbers, about n/2 times.

How Execution Grows With Input

Even though the loop runs n times, the work inside the loop happens only half the time.

Input Size (n)	Approx. Operations
10	10 loop checks, 5 work executions
100	100 loop checks, 50 work executions
1000	1000 loop checks, 500 work executions

Pattern observation: The total loop steps grow linearly with n, and the work inside grows roughly half as fast.

Final Time Complexity

Time Complexity: O(n)

This means the total time grows in a straight line as the input size increases, even with the continue skipping some steps.

Common Mistake

[X] Wrong: "Because continue skips half the work, the time complexity is O(n/2) or less."

[OK] Correct: We ignore that the loop still runs n times, so the total steps still grow linearly with n. Constants like 1/2 do not change the overall growth type.

Interview Connect

Understanding how skipping steps affects loops helps you explain code efficiency clearly and confidently in interviews.

Self-Check

What if we changed the continue condition to skip every third iteration instead of every even one? How would the time complexity change?

Practice

1. What does the continue statement do inside a loop in C#?

easy

A. Stops the entire loop immediately

B. Skips the rest of the current loop iteration and moves to the next one

C. Exits the current method

D. Repeats the current iteration without moving forward

Solution

1. Step 1: Understand the role of continue in loops

   The continue statement tells the loop to skip the remaining code in the current iteration.

2. Step 2: Identify what happens after continue

   After skipping, the loop moves to the next iteration without stopping the whole loop.

3. Final Answer:

   Skips the rest of the current loop iteration and moves to the next one -> Option B

4. Quick Check:

   continue skips current iteration [OK]

Hint: Remember: continue skips current loop step, not whole loop [OK]

Common Mistakes:

• Confusing continue with break
• Thinking continue exits the method
• Assuming continue repeats the iteration

2. Which of the following is the correct syntax to use continue inside a for loop in C#?

easy

A. continue;

B. continue()

C. continue {}

D. continue[]

Solution

1. Step 1: Recall the syntax of continue

   In C#, continue is a statement and must be followed by a semicolon.

2. Step 2: Check each option

   Only continue; is valid syntax. The others use parentheses, braces, or brackets incorrectly.

3. Final Answer:

   continue; -> Option A

4. Quick Check:

   Correct syntax ends with semicolon [OK]

Hint: Use semicolon after continue, no parentheses [OK]

Common Mistakes:

• Adding parentheses after continue
• Using braces or brackets with continue
• Omitting the semicolon

3. What will be the output of the following C# code?

for (int i = 1; i <= 5; i++) {
  if (i == 3) continue;
  Console.Write(i + " ");
}

medium

A. 2 3 4 5

B. 1 2 3 4 5

C. 1 2 3 4

D. 1 2 4 5

Solution

1. Step 1: Analyze the loop and condition

   The loop runs from 1 to 5. When i equals 3, continue skips printing.

2. Step 2: Determine printed values

   Numbers 1, 2, 4, and 5 are printed with spaces. Number 3 is skipped.

3. Final Answer:

   1 2 4 5 -> Option D

4. Quick Check:

   continue skips printing 3 [OK]

Hint: Skip printing when continue triggers, others print [OK]

Common Mistakes:

• Including the skipped number in output
• Confusing continue with break
• Ignoring spaces in output

4. Identify the error in this C# code snippet using continue:

int i = 0;
while (i < 3) {
  if (i == 1)
    continue;
  Console.Write(i);
  i++;
}

medium

A. Syntax error: continue cannot be used in while loop

B. Missing semicolon after continue

C. Infinite loop because i++ is skipped when i == 1

D. Console.Write should be Console.WriteLine

Solution

1. Step 1: Understand loop behavior with continue

   When i == 1, continue skips i++, so i stays 1 forever.

2. Step 2: Identify the problem caused

   The loop never increments i past 1, causing an infinite loop.

3. Final Answer:

   Infinite loop because i++ is skipped when i == 1 -> Option C

4. Quick Check:

   continue skips i++ causing infinite loop [OK]

Hint: Ensure increments run before continue to avoid infinite loops [OK]

Common Mistakes:

• Thinking continue causes syntax error
• Ignoring loop variable increment
• Assuming Console.WriteLine fixes logic

5. You want to print all even numbers from 1 to 10 but skip printing 6 using a for loop and continue. Which code snippet correctly does this?

hard

A. for (int i = 2; i <= 10; i += 2) { if (i == 6) continue; Console.Write(i + " "); }

B. for (int i = 1; i <= 10; i++) { if (i % 2 == 0 && i != 6) Console.Write(i + " "); }

C. for (int i = 2; i <= 10; i++) { if (i % 2 == 0) Console.Write(i + " "); if (i == 6) continue; }

D. for (int i = 2; i <= 10; i += 2) { if (i == 6) break; Console.Write(i + " "); }

Solution

1. Step 1: Understand the goal

   Print even numbers 2,4,8,10 but skip 6 using continue inside a for loop.

2. Step 2: Check each option

   for (int i = 2; i <= 10; i += 2) { if (i == 6) continue; Console.Write(i + " "); } loops by 2, skips 6 with continue, prints others. for (int i = 1; i <= 10; i++) { if (i % 2 == 0 && i != 6) Console.Write(i + " "); } prints all evens except 6 but no continue used. for (int i = 2; i <= 10; i++) { if (i % 2 == 0) Console.Write(i + " "); if (i == 6) continue; } prints 6 because print happens before continue. for (int i = 2; i <= 10; i += 2) { if (i == 6) break; Console.Write(i + " "); } breaks at 6, stopping loop early, so 8 and 10 not printed.

3. Final Answer:

   for (int i = 2; i <= 10; i += 2) { if (i == 6) continue; Console.Write(i + " "); } -> Option A

4. Quick Check:

   Use continue to skip 6 in even-step loop [OK]

Hint: Loop evens, continue at 6 to skip it, print others [OK]

Common Mistakes:

• Using break instead of continue
• Not incrementing by 2 for evens
• Skipping continue and using if only