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Mastering String Manipulation in MATLAB: Tips and Tricks

MATLAB is a popular platform for numerical computation, data analysis, and visualization. It offers various tools and functions to work with data, including strings and character arrays.

In this article, we’ll explore how to manipulate strings in MATLAB, specifically, inserting variable values into strings using num2str() function, joining values using join() and strjoin() functions, and formatting strings using sprintf() function. Inserting Variable Values into Strings:

Often, we need to include variable values in strings for better readability or output formatting.

MATLAB offers the num2str() function to convert variables to strings and concatenate them with other strings. num2str() takes a numeric value as input and returns a string representation of it.

Here’s an example:


n = 42;

str = strcat(‘The answer is ‘, num2str(n));



This will produce an output: The answer is 42. The num2str() function can also take an argument for precision, which specifies the number of significant digits to include in the output.

For instance:


pi_val = pi;

str = strcat(‘The value of pi is approximately ‘, num2str(pi_val, ‘%.4f’));



The %f format specifier is used to indicate that the argument is a floating-point value; %.4f specifies the number of decimal places to print. The output will look like: The value of pi is approximately 3.1416.

Alternatively, we can use the string() function instead of num2str() to convert values to strings. string() function works on both scalar and non-scalar inputs.

To concatenate multiple strings into one, we can use the strcat() function or simply use the plus sign (+) operator with single quotes as follows:


x = 5;

y = 12;

z = x + y;

str = ‘The result is: ‘ + ” ” + string(z);



This will generate an output such as: The result is: 17. Joining Values using Join() and Strjoin() Functions:

We can join values in MATLAB using the join() or strjoin() functions.

The join() function works on vectors and matrices, while the strjoin() function is used for character arrays. Both functions take two arguments: the first is an array of values, and the second is a delimiter character used to separate the values.


v = [1 2 3 4];

joined = join(string(v), ‘, ‘);



This will print: “1, 2, 3, 4”. strjoin() works similarly, but the input array must be a character array, and the delimiter must be a character array or a string.

Here’s an example:


chars = [‘H’ ‘e’ ‘l’ ‘l’ ‘o’];

delimiter = ‘-‘;

joined = strjoin(cellstr(chars), delimiter);



This will print: “H-e-l-l-o.”

Formatting Strings using sprintf() Function:

The sprintf() function allows us to format strings with variable values using format specifications. It takes one or more arguments that correspond to the format specifications and returns a formatted string.

Format specifications are composed of:

– A % character, which indicates the start of a format specifier. – A character that indicates the data type (e.g., d for integers, f for floats, s for strings, etc.).

– Optional flags, such as the precision specifier and alignment specifier. Here’s an example:


price = 19.99;

discount = 0.2;

final_price = price * (1 – discount);

formatted_str = sprintf(‘The final price is $%.2f’, final_price);



This will print “The final price is $15.99”.

Here, the %.2f format specifier indicates a floating-point value with two decimal places. We can also use symbols like %d for integers, %s for strings, etc.


In MATLAB, string manipulation can take many forms, from simple concatenation to complex formatting. The num2str() function and string() function allow for converting variables to strings, while join() and strjoin() functions allow for joining values into strings.

The sprintf() function provides a lot of flexibility in output formatting. Using these functions and their corresponding syntax in MATLAB, manipulating strings and character arrays becomes quite simple and intuitive.

In summary, MATLAB offers several functions to manipulate strings and character arrays, including inserting variable values into strings using num2str() function, joining values using join() and strjoin() functions, and formatting strings using sprintf() function. By utilizing these functions, variable values can be easily incorporated into strings for better readability and output formatting, and strings can be joined and formatted according to specific needs.

These functions are vital for MATLAB users who work with data and need to convey information accurately and concisely. Matlab developers can take away from this article tips for string manipulation in their programs to make their code more readable and easier to understand for other developers.

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