Difference between revisions of "Array"
| Line 1: | Line 1: | ||
| − | --- Syntax --- | + | ---- Syntax ---- |
array[type,d1$,d2$,...,dn] | array[type,d1$,d2$,...,dn] | ||
| − | --- Semantics --- | + | ---- Semantics ---- |
An array, where ''type'' is the element type, followed by the dimensions. The programmer can provide any number of dimensions to create an n dimension array. Default is row major allocation (although this can be overridden via types.) In order to access an element of an array, the programmer can either use the traditional ''name[index]'' syntax or, alternatively ''name#index'' which is preferred | An array, where ''type'' is the element type, followed by the dimensions. The programmer can provide any number of dimensions to create an n dimension array. Default is row major allocation (although this can be overridden via types.) In order to access an element of an array, the programmer can either use the traditional ''name[index]'' syntax or, alternatively ''name#index'' which is preferred | ||
| − | --- Communication --- | + | ---- Communication ---- |
When an array variable is assigned to another, depending on where each variable is allocated to, there may be communication to achieve this assignment. The table details the communication rules for this assignment ''assigned variable := assigning variable''. As with the element type, default communication of arrays is safe. | When an array variable is assigned to another, depending on where each variable is allocated to, there may be communication to achieve this assignment. The table details the communication rules for this assignment ''assigned variable := assigning variable''. As with the element type, default communication of arrays is safe. | ||
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|} | |} | ||
| − | --- Example --- | + | ---- Example ---- |
var a:array[String,2] :: allocated[multiple[]]; | var a:array[String,2] :: allocated[multiple[]]; | ||
Revision as of 19:16, 10 January 2010
Syntax ----
array[type,d1$,d2$,...,dn]
Semantics ----
An array, where type is the element type, followed by the dimensions. The programmer can provide any number of dimensions to create an n dimension array. Default is row major allocation (although this can be overridden via types.) In order to access an element of an array, the programmer can either use the traditional name[index] syntax or, alternatively name#index which is preferred
Communication ----
When an array variable is assigned to another, depending on where each variable is allocated to, there may be communication to achieve this assignment. The table details the communication rules for this assignment assigned variable := assigning variable. As with the element type, default communication of arrays is safe.
| Assigned Variable | Assigning Variable | Semantics |
|---|---|---|
| multiple[] | multiple[] | local assignment |
| single[on[i]] | multiple[] | local assignment on process i |
| multiple[] | single[on[i]] | broadcast from process i |
| single[on[i]] | single[on[i]] | local assignment where i==i |
| single[on[i]] | single[on[j]] | communication from j to i where i!=j |
Example ----
var a:array[String,2] :: allocated[multiple[]]; (a#0):="Hello"; (a#1):="World"; print[(a#0)," ",(a#1),"\n"];
This example will declare variable a to be an array of 2 Strings. Then the first location in the array will be set to Hello and the second location set to World. Lastly the code will display on stdio both these array string locations followed by newline.
