Percent -- % :: Basic Program Components (Programming)

Programming

Percent -- %

The percent sign is most commonly used to indicate nonexecutable text within the body of a program. This text is normally used to include comments in your code. Some functions also interpret the percent sign as a conversion specifier.

See Help Text for more information.

Single Line Comments

Precede any one-line comments in your code with a percent sign. MATLAB does not execute anything that follows a percent sign (that is, unless the sign is quoted, '%'):

% The purpose of this routine is to compute
% the value of ...

Conversion Specifiers

Some functions, like sscanf and sprintf, precede conversion specifiers with the percent sign:

```
sprintf('%s = %d', name, value)
```

Percent-Brace -- %{ %}

The %{ and %} symbols enclose a block of comments that extend beyond one line.

Block Comments

Enclose any multiline comments with percent followed by an opening or closing brace.

%{
The purpose of this routine is to compute
the value of ... 
%}

Note The %{ and %} operators must appear alone on the lines that immediately precede and follow the block of help text. Do not include any other text on these lines.

Semicolon -- ;

The semicolon cnn be used to construct arrays, supress output from a MATLAB command, or to separate commands entered on the same line.

Array Row Separator

When used within square brackets to create a new array or concatenate existing arrays, the semicolon creates a new row in the array:

A = [5, 8; 3, 4]
A =
     5     8
     3     4

Output Suppression

When placed at the end of a command, the semicolon tells MATLAB not to display any output from that command. In this example, MATLAB does not display the resulting 100-by-100 matrix:

```
A = ones(100, 100);
```

Command or Statement Separator

Like the comma operator, you can enter more than one MATLAB command on a line by separating each command with a semicolon. MATLAB suppresses output for those commands terminated with a semicolon, and displays the output for commands terminated with a comma.

In this example, assignments to variables A and C are terminated with a semicolon, and thus do not display. Because the assignment to B is comma-terminated, the output of this one command is displayed:

A = 12.5;  B = 42.7,  C = 1.25;
B =
   42.7000

Single Quotes -- ' '

Single quotes are the constructor symbol for MATLAB character arrays.

Character and String Constructor

MATLAB constructs a character array from all characters enclosed in single quotes. If only one character is in quotes, then MATLAB constructs a 1-by-1 array:

```
S = 'Hello World'
```

See Characters and Strings for more information.

Dot-Dot-Dot (Ellipsis) -- ... Space Character