Using the C++ Math Library

Creating MATLAB Character Arrays

MATLAB represents characters in 16-bit, Unicode format. You can create MATLAB strings using any of the following array creation mechanisms:

• Using an mwArray constructor
• Converting an array of a different type into a character array
• Concatenating existing arrays

The following sections provide more detail about creating arrays with each of these mechanisms, highlighting areas where the C++ syntax is significantly different from the corresponding MATLAB syntax.

Using the Character Array Constructor

The easiest way to create a MATLAB character string is to pass a standard C++ character string to the mwArray string constructor.

mwArray A("my string");

cout << "A = " << A << endl;

This code produces the following output:

'my string'

Converting Numeric Arrays to Character Arrays

To convert a numeric array into a character array, use the char_func() routine. The following code creates an array of numeric values and then converts it into a string.

mwArray C,D;

C = horzcat(109,121,32,115,116,114,105,110,103);

D = char_func(C);

cout << D << endl;

This code produces the following output:

'my string'

To convert this character array back into its underlying numeric representation in double precision format, use the double_func() routine.

Creating Multidimensional Arrays of Strings

You can create a multidimensional array of MATLAB character strings; however, each string must have the same length. The MATLAB C Math Library routines that create arrays of character strings pad the strings with blanks to make them all a uniform length.

Note    To create a multidimensional character array where individual strings aren't padded with blanks, use cell arrays. See page 3-28 for more information.

The following code fragment uses the char_func() routine to create a two-dimensional array of strings from two strings of different lengths.

mwArray Z("my string");
mwArray Y("my dog");

mwArray Q = char_func(Z,Y);

cout << Q << endl;

This code fragment produces the following output. Note how char_func() adds three blanks to the string "my dog" to make it the same length as "my string", creating a 2-by-9 character array.

[
    'my string';
    'my dog   ';
]

Character Arrays

Cell Arrays