Procedural Programming

1. Procedural Programming P1, M1, D1

2. UNIT 16 - Criteria

3. Procedural programming • A list of instructions telling a computer, step-by-step, what to do, usually having a linear order of execution from the first statement to the second and so forth with occasional loops and branches. Procedural programming languages include C, C++, Fortran, Pascal, and Basic.

4. Functions • So far our programs have been fairly short, but as programs become more sophisticated the number of lines of code will increase to hundreds and thousands of lines of codes. We need to have a way to break our program up into manageable chunks (books are broken up into chapters, organisations are broken up into departments, etc) • Sometimes we wish to do the same thing in several different places in our programs and we don’t want to have to go and write the same code all over again (or even have to use the editor copy and paste tools). Sometimes we want to reuse a chunk of code we wrote for a previous job. Sometimes we want to be able to break a program up into chunks and get different people to write different bits and then tie them together at a later date.

5. Example 1 Imagine a program where we want to show the same message to the user in several different places in a program. Enter your age : 11 ************** ***thank you*** ************** Enter your height in metres: 1.64 ************** ***thank you*** ************** Enter your weight in kilograms: 52 ************** ***thank you*** **************

6. Code #include <iostream.h> void thankYou(void); // function prototype void main () { int age; // variables to store age, height and weight float height, weight; cout << “Enter your age: “; cin >> age; thankYou(); // call function cout<<“enter your height in metres: “; cin >> height; thankYou(); // call function cout <<“ Enter your weight in Kilograms: “; cin >> weight; thankYou(); // call function } // end main Void thankYou (void) // function definition { cout <<“**************”<<endl; cout<<“***thank you***”<<endl; cout<<“**************”<<endl; } // end thankYou We have a function prototype, three function calls in the body of main and a function definition The function name is “thankYou” ( you can name it anything you want just like variables but its best to name it meaningful. A function has a return type – in this case it returns nothing so the type is void. A function can have parameters, these are specified in the brackets to right of the function name – this function has no parameters so we put void

7. Task 1 • Write a code calling or displaying Hello world 3 times from a function

8. Example - 2 Imagine program where we want to do the same calculation in several places, such as for the paint program. Enter Length 1: 12 Enter width 1: 5 Area of Side 1 = 60 This function has a float return type It has two parameters named “a” and “b” = both are of type float( you can give parameters any name you want, like variables. It has a local variable (named “temp”) within its definition. #include <iostream> Float SideArea (float a, float b); // function prototype Void main () { float Length1, Width1, Area1; variables to store the length width and area cout<<“Enter Length 1 :”; cin>> Length1 cout<<“Enter Width 1:”; cin>> Width1; Area1 = SideArea( Length1, Width1); // function definition cout<<“the area of side one is:”<<Area1; } // end main Float SideArea (float a, float b) { float temp; // local variables to help with calculations temp = a*b; return temp; } // end SideArea

9. Task 2 • Start creating the paint program and use functions to calculate the area of each side of the room.

10. Why modular programming? • A programming style that breaks down program functions into modules, each of which accomplishes one function and contains all the source code and variables needed to accomplish that function. • Modular programming is a solution to the problem of very large programs that are difficult to debug and maintain. By segmenting the program into modules that perform clearly defined functions, you can determine the source of program errors more easily

11. D1 • Graphical Application: • Think about the help access while playing games?