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The end-loop marker specifies the name of the index variable, which must correspond to the name of the index variable at the start of the for-loop. Some languages (PL/I, Fortran 95, and later) allow a statement label at the start of a for-loop that can be matched by the compiler against the same text on the corresponding end-loop statement.
The post-increment and post-decrement operators increase (or decrease) the value of their operand by 1, but the value of the expression is the operand's value prior to the increment (or decrement) operation. In languages where increment/decrement is not an expression (e.g., Go), only one version is needed (in the case of Go, post operators only).
«for index» «from first» «by increment» «to last» do statements od: APL:While condition statements:EndWhile:Repeat statements:Until condition:For var«s»:In list statements:EndFor:For var«s»:InEach list statements:EndFor: C instructions can be a single statement or a block in the form of: { statements}
A loop invariant is an assertion which must be true before the first loop iteration and remain true after each iteration. This implies that when a loop terminates correctly, both the exit condition and the loop invariant are satisfied. Loop invariants are used to monitor specific properties of a loop during successive iterations.
The types of objects that can be iterated across (my_list in the example) are based on classes that inherit from the library class ITERABLE. The iteration form of the Eiffel loop can also be used as a boolean expression when the keyword loop is replaced by either all (effecting universal quantification) or some (effecting existential ...
A loop can increment a variable and stop when a limit is reached. do index = start [to limit] [by increment] [for count] [instructions] end. The increment value is 1 if the by clause is omitted. The loop continues forever if the limit to clause is omitted, unless terminated earlier by another clause or by a leave statement.
Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. The transformation can be undertaken manually by the programmer or by an optimizing compiler.
The predecessor program changes the variable x 2, which might be in use elsewhere. To expand the statement x 0 := x 1 ∸ 1, one could initialize the variables x n, x n+1 and x n+2 (for a big enough n) to 0, x 1 and 0 respectively, run the code on these variables and copy the result (x n) to x 0. A compiler can do this.