Functions in c++, presentation, short and sweet presentation, and details of functions
- 2. Function Dividing a program into functions. ■ a major principle of top-down, structured programming. ■ To reduce the size of the program. ■ Code re-use. ■ Like C++ operators, a C++ function can be overloaded to make it perform different tasks depending on the arguments passed to it.
- 3. Introduction Void show(); /* Function declaration */ void main() { show(); /* Function call */ } void show() /* Function definition */ { /* Function body */ }
- 4. The main() Function The main() returns a value of type int to the operating system by default. The functions that have a return value should use the return statement for termination. Use void main(), if the function is not returning any value.
- 5. Function Prototyping The prototype describes the function interface to the compiler by giving details such as: The number and type of arguments The type of return values. ■ It is a template ■ When the function is called, the compiler uses the template to ensure that proper arguments are passed, and the return value is treated correctly.
- 6. Each argument variable must be declared independently inside the parentheses. Float avg (int x, int y); // correct float avg (int x, y) ; // illegal ■ In a function declaration, the names of the arguments are dummy variables and therefore they are optional.
- 7. Call by Value Function call passes arguments by value. The called function creates a new set of variables and copies the values of arguments into them. The function does not have access to the actual variables in the calling program and can only work on the copies of values.
- 8. Call by Reference When we pass arguments by reference, the formal arguments in the called function become aliases to the actual arguments in the calling function. This means that when the function is working with its own arguments, it is actually working on theoriginal data.
- 9. Advantages of Functions Easier to Code Easier to Modify Easier to Maintain Reusability Less Programming Time Easier to Understand
- 10. Importance of Function A program may need to repeat the same piece of code at various places. It may be required to perform certain task repeatedly. • The program may become very large if functions are not used. The real reason for using function is to divide program into different parts
- 11. Function Overloading ■Can enables several function ■ Of same name ■ Of different sets of parameters (at least as far as their types are concerned) ■ Used to create several functions of the same name that perform similar tasks but on different data types