whos

List variables in workspace, with sizes and types

Syntax

whos

whos -file filename

whos global

whos ___ var1 ... varN

whos ___ -regexp expr1 ... exprN

S = whos(___)

Description

whos lists in alphabetical order the names, sizes, and types of all variables in the currently active workspace.

whos -file filename lists variables in the specified MAT-file.

Note

Security Considerations: The whos -file command might execute code contained in the MAT-file as it inspects the file. Avoid calling whos -file on untrusted MAT-files.

whos global lists variables in the global workspace.

whos ___ var1 ... varN lists only the specified variables. Use this syntax with any of the arguments in the previous syntaxes.

whos ___ -regexp expr1 ... exprN lists only the variables that match the specified regular expressions.

S = whos(___) stores information about the variables in the structure array S.

Examples

Display Workspace Variable Information

Display information about specific variables in the current workspace. For example, list information about variables with names that start with the letter a.

whos a*

Now, list information about variables with names that end with ion.

whos -regexp ion$

Display Information on Variables Stored in a MAT-File

Display all the information on the variables stored in the sample MAT-file durer.mat.

whos -file durer.mat

  Name           Size               Bytes  Class     Attributes

  X            648x509            2638656  double              
  caption        2x28                 112  char                
  map          128x3                 3072  double              

Store Variable Information in a Structure Array

Store information about the variables in durer.mat in structure array S.

S = whos('-file','durer.mat');

Display the contents of S.

for k = 1:length(S)
   disp(['  ' S(k).name ...
         '  ' mat2str(S(k).size) ...
         '  ' S(k).class]);
end

  X  [648 509]  double
  caption  [2 28]  char
  map  [128 3]  double

Display Variable Attribute Information

Create variables with various attributes, and then display information about them.

Create a file, show_attributes.m, that contains these statements.

function show_attributes
persistent p;
global g;
p = 1;
g = 2;
s = sparse(eye(5));
c = [4+5i 9-3i 7+6i];
whos

Call show_attributes. When MATLAB® executes the whos command at the end of show_attributes, it lists each variable and its corresponding attribute.

show_attributes

  Name      Size            Bytes  Class     Attributes

  c         1x3                48  double    complex   
  g         1x1                 8  double    global    
  p         1x1                 8  double    persistent
  s         5x5               128  double    sparse    

List Workspace Variables Within Nested or Anonymous Function

List all the variables in the current workspace while paused in a nested function.

Create a file, whos_demo.m, that contains these statements.

function whos_demo
date_time = datestr(now,'dd-mmm-yyyy');
 
date_time_array = strsplit(date_time,{'-',''});
get_date(date_time_array);

   function get_date(d)
      day = d{1};  %#ok<*NASGU>
      mon = d{2}; 
      year = d{3}; 
      keyboard
   end

end

Run whos_demo. MATLAB^® pauses at the line with the keyboard command.

whos_demo

K>> 

Call the whos function. MATLAB displays the variables in the nested get_date function, and the variables in all functions that contain the nested function, grouped by function workspace.

K>> whos

Name                 Size            Bytes  Class    Attributes

  ---- whos_demo/get_date ---------------------------------------
  d                    1x3               354  cell               
  day                  1x2                 4  char               
  mon                  1x3                 6  char               
  year                 1x4                 8  char               

  ---- whos_demo ------------------------------------------------
  date_time            1x11               22  char               
  date_time_array      1x3               354  cell               

Input Arguments

var1 ... varN — Variables to display

character vectors | string scalars

Variables to display, specified as one or more character vectors or string scalars. Use the '*' wildcard to match patterns. For example, whos A* S* lists the names of all the variables in the workspace that start with A or S.

expr1 ... exprN — Regular expressions

character vectors | string scalars

Regular expressions that define the variables to display, specified as one or more character vectors or string scalars. For example, whos -regexp ^Mon ^Tues lists only the variable names in the workspace that begin with Mon or Tues. For more information about creating regular expressions, see Regular Expressions.

filename — Name of MAT-file

character vector | string scalar

Name of MAT-file, specified as a character vector or string scalar. The file name can include the full, relative, or partial path. For example, whos -file myFile.mat lists all variables in the MAT-file named myFile.mat. The whos -file filename command does not return the sizes of any MATLAB objects in file filename.

Data Types: char | string

Output Arguments

S — Variable information

nested structure array

Variable information, returned as a nested structure array containing a scalar struct for each variable. Each scalar struct contains these fields.

Field	Description
name	Name of the variable.
size	Dimensions of the variable array.
bytes	Number of bytes allocated for the variable array. whos returns the number of bytes each variable occupies in the workspace, which is not necessarily the same as the number of bytes each variable occupies in a MAT-file. MAT-files Version 7 and later are compressed, so the number of bytes required in the workspace is typically larger than the number of bytes in the file. whos does not report the number of bytes consumed by handle objects. If a variable contains handle objects, the number of bytes that the whos function displays for the variable might be smaller than expected.
class	Class of the variable. If the variable has no value, class is '(unassigned)'.
global	true if the variable is global.
sparse	true if the variable is sparse.
complex	true if the variable is complex.
nesting	Structure with these fields: function — Name of the nested or outer function that defines the variable. level — Nesting level of that function.
persistent	true if the variable is persistent.

Alternatives

• You also can view the contents of MAT-files using the Details Panel of the Current Folder browser. In MATLAB Online™, to view the contents of MAT-files, preview them by clicking the Preview button to the right of the MAT-file in the Files browser.

Extended Capabilities

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The whos function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced before R2006a

R2024b: Improved accuracy of array size information

The whos function returns a more accurate array size measurement in the Bytes column of the displayed list and in the bytes field of the output structure.