1. Normal arrays of characters

2. Converting a list of strings to a cell-arrays of strings

3. Converting a cell-array of strings to a list of strings

StringsArrays of Strings

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1. Vectors of String

Building lists of strings (“vectors” of strings)

Building a list of strings is not as simple as it sounds:

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A = ‘abcd’;B = ‘efg’;C = [A, B];

C =

abcdefg

A = ‘abcd’;B = ‘efg’;C = [A; B];

??? Error using ==> vertcatCAT arguments dimensions are not consistent.

1. Vectors of String, cont.

strvcat() – makes a “column vector” of strings

>> X = strvcat('abc', 'defghi', 'jk') <enter>

X =

abc defghijk

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1. Vectors of String, cont.

strvcat() – makes a “column vector” of strings

>> X = strvcat('abc', 'defghi', 'jk') <enter>

X =

abc defghijk

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Not really a vector – strings are vectors of characters. If combined into a group, it is now a matrix of characters.

Although the 3 strings appear to be of different length, they are not. strvcat() makes each strings identical in length:

a b c

d e f g h i

j k

1. Vectors of String, cont.

Proof by using fprintf()

fprintf('*%s*\n', x(1, :));fprintf('*%s*\n', x(2, :));fprintf('*%s*\n', x(3, :));

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To reference each string, use matrix notation since the vector of strings is really a MATRIX of characters.

(Each row, ALL columns)

1. Vectors of String, cont.

Proof by using fprintf()

fprintf('*%s*\n', x(1, :));fprintf('*%s*\n', x(2, :));fprintf('*%s*\n', x(3, :));

*abc **defghi**jk *

strvcat() “pads” each string with trailing spaces to make them all fit into one rectangular matrix of characters.

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To reference each string, use matrix notation since the vector of strings is really a MATRIX of characters.

(Each row, ALL columns)

Example: data base

Prompt the user for names of AE companies. Store all names in one list of strings. Stop prompting when user enters the string ‘000’.

% initialize all data% ask for a string% while string is not zero-zero-zero

%store at bottom of the list%ask for the next string

% display list of strings

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Example: data base% create an empty listlistCpnies = [];

% ask for a stringcpnyName = input('AE company name (Enter 000 to exit): ', 's');

% while string is not zero-zero-zerowhile

%store at bottom of the list (“vertically concatenate”) %ask for the next stringcpnyName = input('next AE Company name: ', 's');

end

% display list of stringsdisp(listCpnies)

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Example: data base% create an empty listlistCpnies = [];

% ask for a stringcpnyName = input('AE company name (Enter 000 to exit): ', 's');

% while string is not zero-zero-zerowhile ~strcmp(cpnyName, '000')

%store at bottom of the list (“vertically concatenate”)listCpnies = strvcat(listCpnies , cpnyName);%ask for the next stringcpnyName = input('next AE Company name: ', 's');

end

% display list of stringsdisp(listCpnies)

2. Cell-Arrays of String

Why convert a matrix-of-characters to a cell-array-of-strings?

Because many functions (like dialog boxes) require cell-arrays-of-strings as arguments!

cellstr() is a built-in function that easily converts a matrix (or vector) of character to a cell-array of strings.

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Example: listdlg()

From the list of AE companies, convert to a cell-array and ‘pass’ it to a listdlg() function.

%convert list of companies to cell-array

%create dialog box with the list

%continue with code…

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Example: listdlg(), cont.

From the list of AE companies, convert to a cell-array and ‘pass’ it to a listdlg() function.

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Example: listdlg(), cont.

From the list of AE companies, convert to a cell-array and ‘pass’ it to a listdlg() function.

Output:

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Argument MUST be a cell-array, hence the conversion necessary.

Example: listdlg(), end

Continue with code..

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or

Example: listdlg(), end

Continue with code..

Use curly braces {} to refer to the selection number the user chose INSIDE the cell array.

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3. Cell-Arrays to a list

Note that char() is the reverse of cellstr(), it converts a cell-array-of-strings into a list-of-strings (identical length, ended with spaces)

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Wrapping Up

Use strvcat() to create lists of strings. Matlab automatically pads with spaces any string to the length it needs to fit in the matrix.

Use cellstr() to convert a list of strings to one cell-array of strings.

Use char() to convert a cell-array of strings to a list of strings.

Examples shown: Prompt use till ‘000’ entered. Add to a list. Use listdlg()

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