The do-while Statement
- the do-while loop puts Boolean expression after the body of loop
- body will be always executed at least once
- if Boolean expression is TRUE, the loop will continue
- useful for selected applications
- example: read input and check if valid
Common Errors
- extra semicolon after for (..) or while (..) causes zero line infinite loop
- counters (and other variables) not properly initialized
- Boolean expression will never become FALSE (infinite loop)
- loop executes incorrect number of times (off by one common)
- never update for loop counter variable inside for loop
- never use same counter variable for nested loops
Three types of iterative statement are provided in Magma: the for-statement providing definite iteration and the while- and repeat-statements providing indefinite iteration.
Iteration may be performed over an arithmetic progression of integers or over any finite enumerated structure. Iterative statements may be nested. If nested iterations occur over the same enumerated structure, abbreviations such as for x, y in X do may be used; the leftmost identifier will correspond to the outermost loop, etc. (For nested iteration in sequence constructors, see Chapter SEQUENCES.)
Early termination of the body of loop may be specified through use of the `jump' commands break and continue.
