10 Static Variables, Scope, Lifetime

10 Static - Click to edit Master subtitle style Engineering 101 Static Variables Scope Lifetime Quote of the Day Confucius Our greatest glory is

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Unformatted text preview: Click to edit Master subtitle style Engineering 101 Static Variables / Scope / Lifetime Quote of the Day- Confucius Our greatest glory is not in never falling, but in getting up every time we do. Modifications to the n Usually when an identifier is declared the computer sets aside memory in which to store the associated data. n The memory is then available for use. It can be read and altered during the course of the program. n However, sometimes we may want to treat certain data specially. Constants n If you want a variable to never change in the context of the code you can define it to be a const const double speedoflight = 3e8; n Note that const does not replace the type, but rather it modifies the data type. Aliases (References) n We can declare a new variable that is a stand-in for an other variable. double v = 5.0; double & w = v; cout << w << endl; n The above code will print 5.0 because v and w are the same variable. Aliases (References) n We have already used such variables implicitly when we do pass-by-reference. n We can make a reference that is a const. That means that the reference version cannot be changed. double v=5.0; const double & w = v; v = v + 1.0; w = w + 1.0; n This can be useful for passing data without having What is output to the screen? int main() { int A = 10; int & B = A; B = 12; if (A == 10) B = 6; else B = 7; A = 5; 1 – 57 2 – 56 3 – 55 4 – None of the above Scope n Each identifier has a context in which it is meaningful. Outside that context it cannot be referred to or used. This context is called its scope . n Think of it like people in a room and only being able to talk to the people in the room. Scope n An identifier in a compound statement has local scope . It is in scope from the time it is declared to the end of the enclosing braces....
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This note was uploaded on 04/07/2010 for the course ENGR engr 101 taught by Professor Rinenberg during the Spring '10 term at University of Michigan.

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10 Static - Click to edit Master subtitle style Engineering 101 Static Variables Scope Lifetime Quote of the Day Confucius Our greatest glory is

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