Version 0.2.1 (6.74 KB) by Samuel Chan
sprintf() improved -- more readable, concise, and provide advanced formatting.
Updated 7 May 2024


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F-String is like sprintf(), but more readable and concise. It provides a way to interpolate variables and expressions inside a string for formatting. Simply wrap the expressions in curly braces {}, pass the string to f(), and it will return the formatted string. These expressions can include variables, arithmetic operations, function calls, and more.

F-String is inspired by Python f-strings (formatted string literals).


While sprintf() is handy for string formatting, it can be hard to write and read when there are many variables. F-String is simpler:

% sprintf()
sprintf("Product ID: %d, Name: %s, Description: %s, Price: %f, Quantity: %d, Date Added: %s, In Stock: %s", id, name, description, price, quantity, date_added, string(is_in_stock))

% f-string
f("Product ID: {id}, Name: {name}, Description: {description}, Price: {price}, Quantity: {quantity}, Date Added: {date_added}, In Stock: {is_in_stock}")


  • Variables: Variables can be directly inserted into f-strings using curly braces.  (By default, they are converted to string with string().)
>> name = "F-String";
>> f("Hello {name}!")
ans =
    "Hello F-String!"
  • Expressions: Arithmetic operations and function calls can be included within the curly braces.
>> x = 4;
>> f("{1 + sqrt(x)}")
ans =
  • Arrays, Cell Arrays, Structs: They can also be included using curly braces.
>> myArray = [1,2,3];
>> myCellArray = {'a','b','c'};
>> myStruct.a = 10;
>> myStruct.b = 20;
>> f("{myArray(3)} {myCellArray{3}} {myStruct.a} {myStruct.('b')}")
ans =
    "3 c 10 20"
  • Debugging: F-strings can simplify debugging by printing variable names and original expressions along with their values. Simply add = specifier after an expression.
>> device = 'Sensor1';
>> temperatureC = 25.5;
>> humidity = 70.0;
>> f('Readings {device=}, {temperatureC=}°C, {humidity=}%')
ans =
    'Readings device=Sensor1, temperatureC=25.5°C, humidity=70%'

% Spaces in expression and around '=' are respected
>> f('{temperatureC * (9/5) + 32 = }°F')
ans =
    'temperatureC * (9/5) + 32 = 77.9°F'
  • Format specifier: F-strings support advanced formatting options such as specifying type, precision, and field width for the embedded expressions, using MATLAB's format specifier.
>> f('{12648430:%#X}')   % hexadecimal format
ans =

>> f('{0.123456789:%0.3f}')   % precision
ans =

>> f('{123:%5d}')   % field width
ans =
    '  123'

>> f('{22 / 7 = :%0.3f}')   % using both debugging and format specifier
ans =
    '22 / 7 = 3.143'
  • Print Curly Braces: To print curly braces, escape them with double curly braces {{ }}.
>> f('text{{text}}text')
ans =
  • Special Characters: To print special characters, use standard MATLAB escape sequence (see section "Text Before or After Formatting Operators").
>> f("1\t2\n3")
ans =
    "1	2

>> f('unicode heart: \x2665')
ans =
    'unicode heart: ♥'

>> f('50%')   % an exception is that '%' does not need to be escaped
ans =


  • Cell scalars can be embedded in expressions. They are converted to string with string().
>> f("{ {{42}} }")
ans =
  • Arrays cannot be embedded in expressions because they cannot be converted to string with string().
>> f("myArray = {[1,2,3]}")
Error using [string](matlab:matlab.lang.internal.introspective.errorDocCallback('string'))  
Conversion from cell failed. Element 1 must be convertible  
to a string scalar.
  • Nested f-string expressions will work as long as inner quotation marks are escaped the usual MATLAB way:
>> f('<a>{ f("<b>{ f(''c'') }</b>") }</a>')
ans =
  • See FstringTest.m for more use cases.

  • See the f.m source code for how f-string works.


Download the source code from either MATLAB File Exchange or GitHub, unzip if needed, and place f.m somewhere on your MATLAB path.


Thanks to these projects for inspiration:


FString is open-sourced software licensed under the MIT license.

Cite As

Samuel Chan (2024). F-String (https://github.com/Sam-C/fstring/releases/tag/0.2.1), GitHub. Retrieved .

MATLAB Release Compatibility
Created with R2024a
Compatible with R2019b and later releases
Platform Compatibility
Windows macOS Linux

Inspired by: Regular expression based MATLAB Language grammar

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Version Published Release Notes

See release notes for this release on GitHub: https://github.com/Sam-C/fstring/releases/tag/0.2.1


See release notes for this release on GitHub: https://github.com/Sam-C/fstring/releases/tag/0.2.0


To view or report issues in this GitHub add-on, visit the GitHub Repository.
To view or report issues in this GitHub add-on, visit the GitHub Repository.