String concatenation in MATLAB - Step-by-Step Execution

Concept Flow - String concatenation

Start with strings

↓

Use concatenation operator

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Combine strings into one

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Store or display result

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End

This flow shows how MATLAB takes separate strings and joins them into one string using concatenation.

Execution Sample

MATLAB

str1 = 'Hello, ';
str2 = 'world!';
result = [str1 str2];
disp(result);

This code joins two strings "Hello, " and "world!" into one and prints it.

Execution Table

Step	Action	Variable	Value	Output
1	Assign string	str1	'Hello, '
2	Assign string	str2	'world!'
3	Concatenate	result	'Hello, world!'
4	Display	result	'Hello, world!'	Hello, world!

💡 All steps complete, concatenation done and output displayed.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
str1	undefined	'Hello, '	'Hello, '	'Hello, '	'Hello, '
str2	undefined	undefined	'world!'	'world!'	'world!'
result	undefined	undefined	undefined	'Hello, world!'	'Hello, world!'

Key Moments - 2 Insights

Why do we use square brackets [ ] for concatenation in MATLAB?

In MATLAB, square brackets combine arrays or strings horizontally. Here, [str1 str2] joins the two strings into one, as shown in step 3 of the execution_table.

What happens if we forget to use brackets and just write str1 str2?

MATLAB will give an error because it expects an operator or comma between variables. The brackets tell MATLAB to join the strings, as seen in step 3.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'result' after step 3?

A 'world!'

B 'Hello, world!'

C 'Hello,'

D undefined

💡 Hint

Check the 'Value' column for 'result' at step 3 in the execution_table.

At which step is the output 'Hello, world!' displayed?

A Step 2

B Step 3

C Step 4

D Step 1

💡 Hint

Look at the 'Output' column in the execution_table to find when the string is shown.

If we change str2 to 'MATLAB!', what will 'result' be after step 3?

A 'Hello, MATLAB!'

B 'Hello, world!'

C 'MATLAB! Hello, '

D 'Hello, '

💡 Hint

Refer to variable_tracker and understand concatenation order from the code.

Concept Snapshot

String concatenation in MATLAB:
- Use square brackets [ ] to join strings.
- Example: result = [str1 str2];
- Result is a new combined string.
- Use disp(result) to show the string.
- Forgetting brackets causes errors.

Full Transcript

This example shows how MATLAB joins two strings using square brackets. First, str1 is set to "Hello, ", then str2 to "world!". Using [str1 str2], MATLAB concatenates them into "Hello, world!" stored in result. Finally, disp(result) prints the combined string. The key is using brackets to join strings, as MATLAB treats them like arrays. Without brackets, MATLAB cannot combine strings and will error. This step-by-step trace helps beginners see how variables change and when output appears.