Lecture 3

Style guidelines

Reserved words should be in upper case

Use indentation to make code more readable

Identifier - can be a name for a

Variable

Constant

Function

Package

Procedure

Parameter modes

IN - copy – pass by value - actual parameter must have a value

OUT - result – actual parameter doesn’t have to have a value

IN OUT – pass by value/result – similar to pass by reference but not identical

in pass by reference, changes made to formal parameter are immediately

reflected in actual parameter

in pass by value/result, changes made to formal parameters are not

reflected in actual parameter until procedure terminates normally

THUS: if procedure terminates abnormally, no changes are made

to actual parameters

NOTE: even if an array’s parameter mode is IN OUT, the parameter may be passed by reference (to avoid copying the entire array)

Argument is a synonym for parameter

Formal parameters – appear in the heard of functions , procedures and packages

Actual parameters – appear in the function and procedure calls and package instantiations

(identifier : type)

^

|__ parameter mode

Functions return a single value

Formal parameter mode should always be IN

Procedures return zero, one or many values and parameters may be IN, OUT, or IN OUT

headers for function and procedure specifications end in a semi-colon ;

headers for function and procedure bodies end in the reserved word IS

Code examples discussed in class are available as .txt files - let me know if you can’t access them

multiply.adb

testMultiply.adb

printValueWithLabel.adb

testMultiply2.adb