Teach Yourself Borland C++ in 14 Days - portal

SYNTAX
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Getting Your Feet Wet
functions can be used in C++ exactly as they can be used in C. However, C++ takes functions
a bit further. I’ll leave that discussion for now and pick it up again later when we look deeper
into C++.
HOUSE RULES FOR FUNCTIONS
■ A function can take any number of parameters or no parameters at all.
■ A function can be written to return a value, but it is not mandatory that a function
return a value.
■ If a function has a return type of void, it cannot return a value. If you attempt to
return a value from a function with a return type of void, a compiler error will be
issued. A function that returns void need not contain a return statement at all, but
it may if desired. Either way is acceptable. If no return statement is provided, the
function returns automatically when it gets to the end of the function block (the
closing brace).
■ If the function prototype indicates that the function returns a value, the function
body should contain a return statement that returns a value. If the function does
not return a value, a compiler warning is issued.
■ Functions can take any number of parameters but can return only one value.
■ Variables can be passed to functions by value, by pointer, or by reference. (I’ll
discuss this a little later.)
The function statement, in declaration (prototype) format:
ret_type function_name(argtype_1 arg_1, argtype_2 arg_2, ..., argtype_n arg_n);
The function declaration identifies a function that will be included in the code. It shows the
return data type (ret_type) of the function and the name of the function (function_name),
and identifies the order (arg_1, arg_2, …, arg_n) and types (argtype_1, argtype_2, …,
argtype_n) of data arguments the function will expect.
The function statement, in definition format:
ret_type function_name(argtype_1 arg_1, argtype_2 arg_2, ..., argtype_n arg_n) {
statements;
}
The function definition identifies the code block (statements) that makes up the function
and shows the return data type (ret_type) of the function. function_name identifies the
function. The parameters supplied to the function (arg_1, arg_2, …, arg_n) and their types
(argtype_1, argtype_2, …, argtype_n) are included.
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