Functions
Functions in C++ are
programs to perform a specific task. A program is divided into steps or modules
and each module or step can be provided separate function in order to reduce
the complexity of the program. Some points to be considered while writing
functions are : functions be given a name, function name is similar to naming
rules of variables, function name ends with a set of parentheses to help
understand C++ it as a function not a variable, body of the function is
enclosed by braces. When function other than main is invoked the control is
transferred to other function is called function call and when the execution of
that function completes the control is returned to the main function. We may
sometimes need to pass some data to the called functions. There are two ways to
pass the data namely passing by value and passing by address. Passing by value
is the value from main function that is to be used by called function is copied
to the variable of called function, however in case of passing by address the
address of the memory location of function whose contents are to be used in
called function is passed/referred. In passing by address all the processing
takes place on the main data, if the calling function has to effect some
changes/updation to the main function variable, then it does not have to return
the values to the main function and then update the variables there, rather the
main function variables are updated in the calling function, whereas in passing
by value, this does not happen. We use return statement when we need to return some
data from calling function to main function. Syntax is return (data/variable);
we need to declare all the functions before or after the include section of the
program, this is called prototyping. Function recursion is when a function
calls itself repeatedly.
