Passing by Reference

​Using Reference Variables as Parameters

• A mechanism that allows a function to work with the original argument from the function call, not a copy of the argument

• Allows the function to modify values stored in the calling environment

• Provides a way for the function to ‘return’ more than one value

Passing by Reference

• A reference variable is an alias for another variable

• Defined with an ampersand (&)

  • void getDimensions(int&, int&);

• Changes to a reference variable are made to the variable it refers to

• Use reference variables to implement passing parameters by reference

Example

Reference Variable Notes

• Each reference parameter must contain &

• Space between type and & is unimportant • Must use & in both prototype and header

• Argument passed to reference parameter must be a variable – cannot be an expression or constant

• Use when appropriate – don’t use when argument should not be changed by function, or if function needs to return only 1 value