String formatting (sprintf) in MATLAB - Step-by-Step Execution

Concept Flow - String formatting (sprintf)

Start

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Call sprintf with format and values

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Parse format string

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Replace placeholders with values

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Return formatted string

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End

The sprintf function takes a format string and values, replaces placeholders with those values, and returns the formatted string.

Execution Sample

MATLAB

str = sprintf('Hello %s, your score is %d.', 'Alice', 95);

Formats a string inserting a name and a score into placeholders.

Execution Table

Step	Action	Format String	Values	Resulting String
1	Call sprintf	'Hello %s, your score is %d.'	['Alice', 95]	'' (empty, before processing)
2	Parse format string	'Hello %s, your score is %d.'	['Alice', 95]	'' (placeholders identified)
3	Replace %s with 'Alice'	'Hello %s, your score is %d.'	['Alice', 95]	'Hello Alice, your score is %d.'
4	Replace %d with 95	'Hello %s, your score is %d.'	['Alice', 95]	'Hello Alice, your score is 95.'
5	Return formatted string	'Hello %s, your score is %d.'	['Alice', 95]	'Hello Alice, your score is 95.'

💡 All placeholders replaced, formatted string returned.

Variable Tracker

Variable	Start	After Step 3	After Step 4	Final
str	''	'Hello Alice, your score is %d.'	'Hello Alice, your score is 95.'	'Hello Alice, your score is 95.'

Key Moments - 2 Insights

Why does the %s placeholder get replaced before the %d placeholder?

sprintf processes placeholders in order from left to right in the format string, so %s is replaced first as shown in execution_table step 3.

What happens if the number of values does not match the number of placeholders?

sprintf will throw an error or produce unexpected output because each placeholder expects a corresponding value, as implied by the exit_note.

Visual Quiz - 3 Questions

Look at the execution table, what is the string after step 3?

A 'Hello Alice, your score is 95.'

B 'Hello %s, your score is 95.'

C 'Hello Alice, your score is %d.'

D '' (empty string)

💡 Hint

Check the 'Resulting String' column at step 3 in the execution_table.

At which step does sprintf return the final formatted string?

A Step 4

B Step 5

C Step 2

D Step 1

💡 Hint

Look for the step labeled 'Return formatted string' in the execution_table.

If the value 95 was replaced with 100, how would the final string change?

A 'Hello Alice, your score is 100.'

B 'Hello Alice, your score is 95.'

C 'Hello %s, your score is 100.'

D 'Hello %s, your score is %d.'

💡 Hint

Refer to the variable_tracker and imagine changing the value replacing %d.

Concept Snapshot

sprintf(format, values) formats a string by replacing placeholders like %s (string) and %d (integer) with given values.
Placeholders are processed left to right.
Returns the formatted string without printing.
Useful for building strings with variables.
Example: sprintf('Hi %s, %d', 'Bob', 10) -> 'Hi Bob, 10'.

Full Transcript

This visual execution shows how MATLAB's sprintf function works step-by-step. First, sprintf is called with a format string containing placeholders and values to insert. It parses the format string, identifies placeholders like %s and %d, then replaces them one by one with the provided values in order. The variable 'str' changes from empty to the final formatted string 'Hello Alice, your score is 95.' The process ends when all placeholders are replaced and the string is returned. Common confusions include the order of replacement and matching values to placeholders. The quizzes test understanding of intermediate string states and final output.