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--- language:langs:chp [2023/04/07 08:19]
rajit [Syntactic replication]
+++ language:langs:chp [2023/04/09 19:26]
rajit [Conditional execution]
@@ Line 86: / Line 86: @@
 In the published literature, non-deterministic selections are usually written using a thin bar ''|'' rather than the thick bar ''[]''. However, this can create some ambiguities in parsing. For example, consider the statement ''[ a -> y:=b | c | d -> skip ]''. This can be parsed in a number of ways, and it is not clear which one was the intended option.
+===== Arrays: dynamic v/s non-dynamic indices =====
+Suppose an array ''x'' has been declared as:
+<code act>
+int x[10];
+</code>
+Now when ''x'' is accessed in CHP, it could be accessed with an array index that is a run-time constant, or an index that is computed at run-time. For example, the CHP program
+<code act>
+chp {
+   ...
+   x[0] := x[0] + 1;
+   ...
+}
+</code>
+uses ''x'' with a constant index. As opposed to this, the program
+<code act>
+chp {
+   ...
+   x[i] := x[i] + 1;
+   ...
+}
+</code>
+uses ''x'' with an index that is computed using the run-time value of ''i''. This second category of arrays are referred to as //dynamic arrays//---not because the array size is dynamic, but because the element of the array accessed depends on a value that is computed by the circuit.
 ===== Loops =====
@@ Line 286: / Line 312: @@
 *[ C?c; [ ([] i : N : c = i -> I[i]?d) ]; O!d ]
 </code>
-where ''N'' is the number of channels in the ''I'' array.
+where ''N'' is the number of channels in the ''I'' array. This approach ensures that index for the array ''I[]'' is always a constant.
 ====== The chp-txt sublanguage ======