What is the difference between the declaration and the definition of a variable

What is the difference between the declaration and the definition of a variable?

The definition is the one that actually allocates space, and provides an initialization value, if any.
There can be many declarations, but there must be exactly one definition. A definition tells the compiler to set aside storage for the variable. A declaration makes the variable known to parts of the program that may wish to use it. A variable might be defined and declared in the same statement.


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