On this page 
Overview
VEX includes an array datatype. This is useful in several places:

Supporting ramp parameters.

Reading capture data from surface nodes using the import() function.

General programming, wherever arrays would be useful.
Note
Currently VEX does not support multidimensional arrays.
This example shows off some of the crazy things that you can do with arrays:
surface crazy( string maps[] = { "Mandril.rat", "default.pic" }; export float alength = 0; ) { vector texclr, av[]; texclr = texture(maps[s+t > 1], s, t); av = array( {1,0,0}, vector(nrandom()), t, texclr, {.5,0,0}); if (fit(noise(s*8), 0, 1, .3, .7) > t) av = array(1, {0,1,0}, 0); Cf = spline("linear", s, av); alength = len(av); }
Declaring array types
To declare an array variable, the general form is
member_type var_name[]
:
// my_array is an array of floats float my_array[]; // v is a single vector, vector_array is an array of vectors vector v, vector_array[]; // str_array is an array of strings string str_array[];
You can optionally put a size inside the square brackets, but the VEX compiler currently ignores it.
To declare a function that returns an array:
// A function which returns an array of vectors vector[] rgb_array() { ... };
To declare a nested function that returns an array:
// A function which returns an array of vectors cvex foo() { // Use the optional 'function' keyword to avoid type ambiguity function vector[] rgb_array() { ... }; }
To specify a literal array, use curly braces, with the array members separated by commas:
vector an_array[] = { {1, 2, 3}, {2, 3, 4}, {4, 5, 6} }; vector[] rgb_array() { return { {1, 0, 0}, {0, 1, 0}, {0, 0, 1} }; }
Note
Literal arrays are constructed at compile time, so they cannot include variables.
For example, this is an error:
int arr[] = { my_var, other_var + 2 }; // Error
To avoid this error, use the array()
function which constructs
the array at runtime from any number of arguments:
int arr[] = array( my_var, other_var + 2 );
If you specify scalars where a vector is expected, the compiler assigns the scalar value to all components of the vector:
vector an_array[] = { 1, 2, 3}; // an_array[] == { {1, 1, 1}, {2, 2, 2}, {3, 3, 3} }
The array()
function creates an array from its arguments.
int my_array[] = array(1, 2, 3, 4, 5);
You can use array()
to generate an array of any type.
To force array()
to generate vectors (for example):
vector (array (value1, value2, ...) );
Accessing and setting array values
Use arrayname[index]
to look up a value by its position in the
array.
vector bw[] = { 0, 1 }; // bw[] == { {0, 0, 0}, {1, 1, 1} } Cf = bw[index];
Array bounds are checked at run time. Reading out of bounds will return 0
or
""
. This may generate a warning or optional runtime error in the future.
Writing past the end of an array will resize the array to include the
index written to. The new entries will be set to 0
or ""
.
Pythonstyle indexing is used. This means negative indices refer to positions from the end of the array.
int nums[] = { 0, 1, 2, 3, 4, 5 }; int n = nums[10]; // Returns 0 int b = nums[2]; // Returns 4 string strs[] = { }; string s = strs[20]; // Returns ""
You can also assign values using the square brackets notation:
float nums[] = { }; nums[0] = 3.14;
(The getcomp and setcomp functions are equivalents for using the square brackets notation.)
Note
The squarebrackets operator also works on vectors. You can use it with
matrices as well using a pair of brackets: float a = m3[0][1];
Slicing Arrays
The squarebrackets can be used to extract subarrays using the Python slicing notation.
int nums[] = { 0, 1, 2, 3, 4, 5 }; int start[] = nums[0:2]; // { 0, 1 } int end[] = nums[2:]; // { 4, 5 } int rev[] = nums[::1]; // { 5, 4, 3, 2, 1, 0 } int odd[] = nums[1::2]; // { 1, 3, 5 }
The slice function is the equivalent for using the slicebased square brackets notation.
Copying between arrays and vectors/matrices
The assignment operator supports assigning values between vector types and arrays of floats:
float x[]; // Cf and P are vectors x = set(P); // Assigns the components of P to the corresponding // members of the array x Cf = set(x); // Assigns the first 3 members of x as the // components of the vector Cf
If the array is not long enough to fill the vector/matrix, the last member is repeated as often as necessary.
float x[] = {1, 2} // Not long enough to fill a vector Cf = set(x); // Cf == {1, 2, 2}
You can also assign between matrix types and arrays of vector2
/vector
/vector4
:
vector2 v2[]; vector v[]; vector4 v4[]; matrix2 m2 = 1; matrix3 m3 = 1; matrix m4 = 1; v = set(m3); // Each row of the 3x3 matrix is put into a vector m3 = set(v); // Copy the vectors into the row vectors of the matrix v4 = set(m4); // Extract the rows of the matrix into the vector4 array m4 = set(v4); // Create a matrix using the vector4's in the array as row vectors
In summary:
Left side =  Right side  Notes 

vector2

float[]

E.g. vector2 v = {1,2}

vector

float[]

E.g. vector v = {1,2,3}

vector4

float[]

E.g. vector4 v = {1,2,3,4};

matrix2

float[]

E.g. matrix2 m = {1,2,3,4};

matrix2

vector2[]

E.g. matrix2 m = { {1,2}, {4,5} };

matrix3

float[]

E.g. matrix3 m = {1,2,3,4,5,6,7,8,9};

matrix3

vector[]

E.g. matrix3 m = { {1,2,3}, {4,5,6}, {7,8,9}};

matrix

float[]

E.g. matrix m = {1,2,3,4,5,6,7,8,9.., 16};

matrix

vector4[]

E.g. matrix m = { {1,2,3,4}, {5,6,7,8}, ... {13,14,15,16}};

float[]

vector2

Create an array of 2 floats from the components 
float[]

vector

Create an array of 3 floats from the components 
float[]

vector4

Create an array of 4 floats from the components 
float[]

matrix2

Create an array of 4 floats from the matrix2 
vector2[]

matrix2

Create an array of 2 vector2s from the matrix2 
float[]

matrix3

Create an array of 9 floats from the matrix3 
vector[]

matrix3

Create an array of 3 vectors from the matrix3 
float[]

matrix4

Create an array of 16 floats 
vector4[]

matrix4

Create an array of 4 vector4 s.

Looping over an array
See foreach.
Working with arrays
The following functions let you query and manipulate arrays.
Sets the length of the array. If the array is enlarged, intermediate values
will be 0
or ""
.
Returns the length of an array.
Removes the last item from the array (decreasing the size of the array by 1) and returns it.
Removes the first instance of a value in the array. Returns 1
if an item was removed, or 0
otherwise.
Adds an item to the end of an array (increasing the size of the array by 1).
Gets the value of an array component, the same as array[num]
.
Sets the value of an array component, the same as array[num] = value
.
Efficiently creates an array from its arguments.
Flattens an array of vectors or matrices into an array of floats.
Reverses the effect of serialize: assembles a flat array of floats into an array of vectors or matrices.
An arraybased replacement for the neighbourcount/neighbour combo. Returns an array of the point numbers of the neighbors of a given point.
In addition, the following functions work with arrays:
VCC pragmas
The ramp
pragma lets you specify a ramp user interface for a set of
parameters.
#pragma ramp <ramp_parm> <basis_parm> <keys_parm> <values_parm>
See VCC pragmas for more information.
Limitations

Currently VEX does not support multidimensional arrays.

Arrays cannot be passed between shaders (through simport, etc.).

Arrays cannot be written to image planes.