Code Generation for Strings

Code generation supports 1-by-1 MATLAB^® string arrays. Code generation does not support string arrays that have more than one element.

A 1-by-1 string array, called a string scalar, contains one piece of text, represented as a 1-by-n character vector. An example of a string scalar is "Hello, world". For more information about strings, see Text in String and Character Arrays.

Limitations

For string scalars, code generation does not support:

• Global variables

• Indexing with curly braces {}

• Missing values

• Defining input types programmatically by using preconditioning with assert statements

• Their use with coder.varsize, when generating code by using the codegen (MATLAB Coder) command, the fiaccel command, or the MATLAB Coder™ app

• Their use as Simulink^® signals, parameters, or data store memory

For code generation, limitations that apply to classes apply to strings. See MATLAB Classes Definition for Code Generation.

Differences Between Generated Code and MATLAB Code

• Converting a string that contains multiple unary operators to double can produce different results between MATLAB and the generated code. Consider this function:

  function out = foo(op)
  out = double(op + 1);
  end

  For an input value "--", the function converts the string "--1" to double. In MATLAB, the answer is NaN. In the generated code, the answer is 1.

• Double conversion for a string with misplaced commas (commas that are not used as thousands separators) can produce different results from MATLAB.