For loops · Procedural

Build the idea

Start with the concept and its key vocabulary.

Key idea

Trace and write count-controlled loops with equivalent ERL and Python bounds.

Use a for loop when the number of repetitions is known. OCR ERL includes both values written after for and to. Python range() excludes its stop value, so ERL 0 to 4 becomes Python range(5). The loop variable takes each value in turn before the body runs.

Iteration

Repeating a set of instructions.

Count-controlled loop

A loop that repeats a known number of times.

Loop variable

A variable whose value changes automatically for each pass through a for loop.

range()

A Python function that produces the values used by a for loop; its stop value is excluded.

Keep these in mind

ERL closes a for loop with next followed by the loop variable.
The final value after ERL to is included.
The stop value supplied to Python range() is excluded.
Indented Python instructions form the repeated loop body.

Build the idea

Start with the concept and its key vocabulary.

Key idea

Trace and write count-controlled loops with equivalent ERL and Python bounds.

Iteration

Repeating a set of instructions.

Count-controlled loop

A loop that repeats a known number of times.

Loop variable

A variable whose value changes automatically for each pass through a for loop.

range()

A Python function that produces the values used by a for loop; its stop value is excluded.

Keep these in mind

ERL closes a for loop with next followed by the loop variable.
The final value after ERL to is included.
The stop value supplied to Python range() is excluded.
Indented Python instructions form the repeated loop body.