This program illustrates the "FIFO" (First In, First Out) behavior
of a simple queue of characters, as well as its default constructor,
its copy constructor, and the queue push(), pop(), front(), back(),
empty(), and size() member functions.
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The queue q1 contains 4 values.
The front value is A and the back value is D.
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The queue q2 is created as a copy of q1, after which another value is added,
so its size is 5.
The front value is A and the back value is E.
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Here the values of q1, in "FIFO" order:
Popping: A
Popping: B
Popping: C
Popping: D
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Here the values of q2, in "FIFO" order:
Popping: A
Popping: B
Popping: C
Popping: D
Popping: E
Press Enter to continue ...