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Statements

Statements. Presented by Quentin Ochem. university.adacore.com. Some General Information. Statements can be spread on several lines, and need to be completed by a ; Statements need to be written in a sequence of statement. If Statements / If Expressions. If statements If expressions. Ada.

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Statements

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  1. Statements Presented by Quentin Ochem university.adacore.com

  2. Some General Information • Statements can be spread on several lines, and need to be completed by a ; • Statements need to be written in a sequence of statement

  3. If Statements / If Expressions • If statements • If expressions Ada C++ C++ Ada

  4. Condition Operators • Comparison • Binary Boolean Operators and Short Circuit Forms

  5. A Note on the Binary Boolean Operators • “and”, “or” are not short-circuit, both operands are always evaluated • Short-circuit execution is used for “and then” and “or else”

  6. Case Statement / Case Expression Ada C++

  7. Case Statements Rules • All values covered by the type of the expression should be covered • Values must be unique

  8. Loop Statement • Loop is introduced by the loop / end loop block • Loop can be controlled by a exit condition through a while statement

  9. Exit Statements • At any time, a loop can be broken by an exit statement • In case of nested loops, names can be given to exit an outer loop

  10. For .. Loop • Iteration can be done over a range • The range is always given in ascending order • The iteration always goes to the successor, or predecessor if reverse is specified

  11. For .. Loop Control Variable • The variable declared in the for loop can be explicitly typed • It may be of any discrete type. When no range is specified, the whole type range is taken • The control variable is constant in the loop

  12. For .. Loop Range Evaluation • The loop range is evaluated once, when entering the loop

  13. Declare Blocks • In any sequence of statements, it may be useful to re-open declarative blocks or a sub sequence of expressions (for new variable declaration, exception handlers…) • Can be done through a new declare bock

  14. Null Statements • It is illegal to have an empty sequence of statements but … • … it’s possible to use a statement that does nothing, the null statement

  15. (1/10)

  16. (1/10) Compilation error, = is the equality symbol in Ada

  17. (2/10)

  18. (2/10) Compilation error, := is not an operator, can’t be usedin a condition

  19. (3/10)

  20. (3/10) Compilation error, 0 value is missing

  21. (4/10)

  22. (4/10) Compilation Error, 1 .. Integer'Last and 0 .. Integer'Last overlaps

  23. (5/10)

  24. (5/10) Compilation Error, the value evaluated must be discrete

  25. (6/10)

  26. (6/10) Compilation Error, I is constant in the loop, assignment is forbidden

  27. What is the output of this code? (7/10)

  28. What is the output of this code? (7/10) Nothing, the loop has an empty range, needs “reverse 0 .. 10” to be backwards.

  29. (8/10)

  30. (8/10) Compilation Error, the Ada inequality symbol is “/=“

  31. (9/10)

  32. (9/10) Correct, although the I declaration is redundant

  33. What is the output of this code? (10/10)

  34. What is the output of this code? (10/10) “A” / the range is evaluated before entering the loop

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