Variable-Size Data

Definition, differences for code generation, dynamic memory allocation

Variable-size data is data whose size is not known at compile time or changes at run time. To use variable-size data in your MATLAB^® code for which you intend to generate C/C++ code, follow the described guidelines. Certain restrictions apply to the use of variable-size data in MATLAB code that is intended for code generation. These techniques can help you to control dynamic memory allocation and improve performance of the generated code.

Functions

`coder.areUnboundedVariableSizedArraysSupported`	Check if current configuration settings allow unbounded variable-size arrays (Since R2024a)
`coder.varsize`	Declare variable-size data

Topics

Code Generation for Variable-Size Arrays
Variable-size data is data whose size is not known at compile time or whose size can change at run time.
Define Variable-Size Data for Code Generation
Choose a method for defining variable-size data.
Control Memory Allocation for Variable-Size Arrays
Control when dynamic memory allocation is used.
Control Dynamic Memory Allocation for Fixed-Size Arrays
Control when to dynamically allocate memory for fixed-size arrays.
Generate Code for Variable-Size Data
Generate code for data whose size might change at run time.
Specify Upper Bounds for Variable-Size Arrays
To avoid dynamic memory allocation, specify upper bounds for a variable-size array.
Use C Arrays in the Generated Function Interfaces
Understand and use arrays from the generated function interfaces
Incompatibilities with MATLAB in Variable-Size Support for Code Generation
Sometimes, the results for variable-size data in generated code are different than the results in MATLAB.
Variable-Sizing Restrictions for Code Generation of Toolbox Functions
Some restrictions for variable-size data apply to multiple toolbox functions.

Troubleshooting

Diagnose and Fix Variable-Size Data Errors

Troubleshoot size mismatch and upper bounds detection errors.