Functions provide a way to modularize code and make it easier to maintain. Also, functions promote code reuse.
All C programs have one (at least the main() function is required) or more functions.
Functions can accept parameters from the code that calls them.
Functions usually return a single value.
Functions help to organize a program into logical, manageable segments.
Syntax
type identifier (type1 arg1, type2 arg2, ..., typen argn) {
declarations // body
statements // body
return expression; // body
}
Where:
type is the data type of the return expression.identifier is the name of the function.type1 arg1, type2 arg2, ..., typen argn is the parameter list which is optional.expression is the (optional) return value.