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ITEC 320 Lecture 4 Sub-Types Functions

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Functions / Procedures Review Types Homework Questions?

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Functions / Procedures Outline Subtypes / Enumerated types Procedures Functions Problems

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Functions / Procedures Compiler tasks Compile time –What errors are caught? Run-time –What errors are caught

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Functions / Procedures New types Example type Temperature is range 32.. 212; type Pressure is range 0.. 500; t: Temperature; p: Pressure; t := 100; -- valid p := t; -- compile error

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Functions / Procedures Enumerated types Map an int to a word procedure enum_demo is type Color is (red, blue, green); c: color := green; begin if c = blue then -- do something end if; c:=0; --What happens here? end enum_demo;

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Functions / Procedures Modular Types What do you think this is used for type ClockHourType is mod 12; startTime: ClockHourType := 10; breakTime: ClockHourType := startTime + 2; -- 0 endTime: ClockHourType := startTime + 4; -- 2

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Functions / Procedures Floating point Example type Money is delta 0.01 digits 15; cent: Money := 0.01; dollar: Money := 0.0; for i in 1.. 100 loop dollar := dollar + cent; end loop; put(float(dollar)); -- 1.00

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Functions / Procedures In-class Let's write a program in groups: Read a low and a high value to define a range, and then read a sequence of numbers, until eof, and count the number of numbers below, in, and above the range. Calculate the percent in each group. Assume the endpoints of the range are in the range. Output, nicely formatted, the counts and percents.

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Functions / Procedures Functions Similar to java methods with a non-void return type Must have a return type Must be defined before use Cannot modify parameters

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Functions / Procedures Syntax function sumArray(a: Int_Array) return integer is s: Integer := 0; -- holds the sum begin for i in a'range loop s := s + a(i); end loop; return s; end sumArray;

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Functions / Procedures Procedure s No return type allowed Parameters can be changed –In (default) –Out (allows passing back to the caller) –In Out (pass in and out) What about the get procedure’s parameter? Structure charts help

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Functions / Procedures Syntax with ada.text_io; use ada.text_io; with ada.integer_text_io; use ada.integer_text_io; procedure inout is procedure vars(a: in Integer; b: in out Integer; c: out Integer) is begin b:= b+a; c:= b+3; end vars; x: Integer; y: Integer; z: Integer; begin x:=2; y:=3; vars(x,y,z); put(x'img & "|" & y'img & "|" & z'img); end inout;

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Functions / Procedures Issues Assigning to an in parameter Using an out parameter’s values in the procedure (by default it can be anything) Forgetting to assign a value to an out parameter Can’t fool variables –I.e. passing an in mode variable to another procedure where it is an out mode parameter

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Functions / Procedures Problems Write a function/procedure that returns whether or not a String is a palindrome

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Functions / Procedures Problems Given n of 1 or more, return the factorial of n, which is n * (n-1) * (n-2)... 1. Compute the result recursively (without loops).

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Functions / Procedures Summary Functions Procedures

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