QUESTION 07 · Functions
Actual arguments are expressions supplied in a call. Formal parameters are the variables declared in the function definition to receive their values.
QUESTION 08 · Functions
Functions communicate by receiving argument values, returning a value and, when appropriate, accessing objects through pointers or shared declarations.
An argument is an expression written in the call. In add(x, 5), the value of x and the value 5 are supplied. An argument can be a constant, variable or a more complex expression, provided its type and use are suitable for the function.
Parameters are declared in the function definition. In int add(int a, int b), a and b are separate local parameter objects for each call. Their names need not be the same as the caller’s variable names. C passes values: changes to a or b alone do not change the caller’s ordinary integer variables.
return expression; supplies one result value to the caller for a non-void function. The caller can assign that result to a variable, print it or use it in another expression. The return type describes the kind of result.
If x contains 4, add(x, 5) supplies 4 and 5. The parameter objects receive those values. The function returns 9. If the caller writes result = add(x, 5);, result becomes 9 while x remains 4.
Use a visible prototype and compatible types. C does not generally specify the order in which different argument expressions are evaluated. Avoid calls that update the same variable in conflicting argument expressions. Prefer clear, independent arguments. Pointer-based output is introduced separately; the pointer value is still passed by value.
Related questions in the function declarations category from the supplied papers. The marks below are the printed allocations, including any combined subquestion.
Define function signature.
Paper P05 · page 1What is the signature of a function?
Paper P06 · page 1