Break and continue in MATLAB - Mini Project: Build & Apply

Using Break and Continue in MATLAB Loops

📖 Scenario: You are analyzing a list of daily temperatures to find specific conditions. Sometimes you want to stop checking once a certain temperature is found, or skip days that don't meet a condition.

🎯 Goal: Build a MATLAB script that uses break and continue statements inside a for loop to process temperature data.

📋 What You'll Learn

Create a vector called temperatures with exact values

Create a variable called threshold to set a temperature limit

Use a for loop with continue to skip temperatures below the threshold

Use break to stop the loop when a temperature equals 100

Print the temperatures processed before stopping

💡 Why This Matters

🌍 Real World

Analyzing temperature data to quickly find important values or skip irrelevant data is common in weather monitoring and control systems.

💼 Career

Using <code>break</code> and <code>continue</code> helps programmers write efficient loops that handle real-world data with conditions, a key skill in data analysis and engineering.

1

Create the temperature data vector

Create a vector called temperatures with these exact values: [72, 85, 90, 100, 95, 88]

MATLAB

% Create the vector temperatures with the given values

Hint

Use square brackets to create a vector in MATLAB.

2

Set the temperature threshold

Create a variable called threshold and set it to 80

MATLAB

temperatures = [72, 85, 90, 100, 95, 88];
% Create the variable threshold and set it to 80

Hint

Just assign the number 80 to the variable threshold.

3

Use break and continue in a for loop

Write a for loop using variable i from 1 to length of temperatures. Inside the loop, use continue to skip temperatures less than threshold. Use break to stop the loop if the temperature equals 100. Store processed temperatures in a vector called processed.

MATLAB

temperatures = [72, 85, 90, 100, 95, 88];
threshold = 80;
% Write the for loop with break and continue below

Hint

Use continue to skip adding temperatures below threshold. Use break to stop when temperature is 100.

4

Display the processed temperatures

Write a disp statement to display the vector processed

MATLAB

temperatures = [72, 85, 90, 100, 95, 88];
threshold = 80;
processed = [];
for i = 1:length(temperatures)
    if temperatures(i) < threshold
        continue
    end
    if temperatures(i) == 100
        break
    end
    processed(end+1) = temperatures(i);
end
% Display the processed vector

Hint

Use disp(processed) to show the vector.

Practice

1. What does the break statement do inside a MATLAB loop?

easy

A. Stops the entire loop immediately and exits it.

B. Skips the current iteration and continues with the next one.

C. Restarts the loop from the beginning.

D. Pauses the loop until a condition is met.

Solution

1. Step 1: Understand the purpose of break

   The break statement is used to exit a loop immediately, no matter where it is in the loop.

2. Step 2: Compare with other loop controls

   Unlike continue, which skips only the current iteration, break stops the whole loop.

3. Final Answer:

   Stops the entire loop immediately and exits it. -> Option A

4. Quick Check:

   break = stop loop [OK]

Hint: Break stops loop fully; continue skips one step [OK]

Common Mistakes:

• Confusing break with continue
• Thinking break only skips one iteration
• Believing break restarts the loop

2. Which of the following is the correct syntax to skip the current iteration in a MATLAB for loop?

easy

A. continue;

B. next;

C. break;

D. skip;

Solution

1. Step 1: Identify the statement to skip iteration

   In MATLAB, continue is the keyword used to skip the rest of the current loop iteration and move to the next.

2. Step 2: Check other options

   break exits the loop, skip and next are not valid MATLAB keywords.

3. Final Answer:

   continue; -> Option A

4. Quick Check:

   continue = skip iteration [OK]

Hint: Use continue to skip current loop step [OK]

Common Mistakes:

• Using break instead of continue
• Writing skip or next which are invalid
• Omitting the semicolon (though optional)

3. What will be the output of this MATLAB code?

sum = 0;
for i = 1:5
    if i == 3
        break;
    end
    sum = sum + i;
end
sum

medium

A. 10

B. 3

C. 6

D. 15

Solution

1. Step 1: Trace the loop iterations

   The loop runs i = 1, 2, then at i = 3 the break triggers and loop stops.

2. Step 2: Calculate sum before break

   sum = 0 + 1 + 2 = 3; The addition at i=3 does not happen because break stops loop before sum update.

3. Final Answer:

   3 -> Option B

4. Quick Check:

   Sum before break = 3 [OK]

Hint: Break stops loop before adding i=3 [OK]

Common Mistakes:

• Adding i=3 before break
• Summing all numbers ignoring break
• Confusing break with continue

4. Find the error in this MATLAB code snippet:

for i = 1:5
    if i == 3
        continue
    end
    disp(i)
end

medium

A. Missing semicolon after continue

B. disp(i) will not display 3

C. No error, code runs correctly

D. continue cannot be used inside for loops

Solution

1. Step 1: Check syntax of continue

   In MATLAB, continue does not require a semicolon and is valid inside loops.

2. Step 2: Understand loop behavior

   When i == 3, continue skips disp(i), so 3 is not displayed. This is expected behavior.

3. Final Answer:

   No error, code runs correctly -> Option C

4. Quick Check:

   continue valid in loops [OK]

Hint: Continue works without semicolon in loops [OK]

Common Mistakes:

• Thinking semicolon is mandatory after continue
• Believing continue is invalid in for loops
• Expecting disp to print 3

5. You want to sum numbers from 1 to 10 but skip adding 5 and stop the loop if the sum exceeds 30. Which code correctly uses break and continue?

hard

A. sum = 0;
for i = 1:10
if sum > 30
continue;
elseif i == 5
continue;
end
sum = sum + i;
end

B. sum = 0;
for i = 1:10
if i == 5
break;
elseif sum > 30
continue;
end
sum = sum + i;
end

C. sum = 0;
for i = 1:10
if sum > 30
continue;
elseif i == 5
break;
end
sum = sum + i;
end

D. sum = 0;
for i = 1:10
if i == 5
continue;
end
sum = sum + i;
if sum > 30
break;
end
end

Solution

1. Step 1: Understand conditions order

   We must skip adding 5 (continue when i==5) and stop loop if sum > 30 (break after adding).

2. Step 2: Analyze each option

   sum = 0; for i = 1:10 if i == 5 continue; end sum = sum + i; if sum > 30 break; end end skips 5 before adding, then adds i, then checks sum > 30 to break. This matches requirements.

3. Final Answer:

   C -> Option D

4. Quick Check:

   Skip 5 with continue; break after sum check [OK]

Hint: Continue before add to skip; break after add to stop [OK]

Common Mistakes:

• Breaking when i==5 instead of continuing
• Checking sum > 30 before adding
• Using continue to skip after sum check