Step by Step Guide To Learn How To Program

1. Different programming languages each have their own syntax and appearance, but my concern here is to acquaint you with the basic nature of programs and how to write and understand them. These concepts are pretty much the same  in all languages. (C++, Java etc.)
2. In my illustrations below, I will follow the Java syntax
3. Make up variable names to hold values in the program
4. Use Variable names that are easy to identify
5. These variables will take on values when the program executes  -- plan ahead
   so you can create variables that you will need to make the program function.
   This is a hard task because you need to be able to envision the program executing.
   You have to write the commands or steps for this execution. Different tools such as flowcharts can help in this task but basically you have to be able to see the solution to the problem and write the steps to make it happen. -- HARDEST THING FOR STUDENTS TO LEARN.
6. Beginning programmers will normally be told WHAT THE PROGRAM IS EXPECTED TO PRODUCE and WHAT THINGS OR DATA THE PROGRAM HAS TO WORK WITH.
7. In essence, program will process data and produce output results. Keep this in mind
   as you review all the code that follows.
8. I will use // for comments in all the code examples that follow Comments are for documentation purposes only and do not affect a program's execution.
9. The programmer then starts to create variables and uses the commands for the specific language to solve the problem.
10. Data that is to be processed is normally put into variables in one of two ways:
    ... ASSIGNED           denoted by an = sign.
    ... INPUTTED    from the keyboard or from a file
11. Remember that a variable can hold only one thing at a time for example someone's age, weight, name, address  etc.
12. We have different types of variables based upon the type of data that they can hold.
13. Common types are integer, float, Char, String, Boolean.
14. Integers hold whole numbers
    Floats hold numbers involving decimal points
    Char holds one character like 'M'  or 'F'
    Strings hold groups of characters like people's names
    Boolean holds true or false state  not "true" but value true.
15. The actual commands in a programming language are simple to understand
    and there are not very many of them
16. Command in a language can t\really be broken down into 4 types
    Commands for assigning data to variables
    commands for inputting data into variables
    Commands for outputting the data that is in variables
    Commands for controlling the order of processing the above three Command types
17. In short, the actual commands in a programming language are easy to understand.
    It is truly understanding the concept of variables and how to use them, that is difficult for the beginning programmer.
18. Students must accept the fact that the computer only does one thing at a time.
    It just does it extremely fast. (Like millions of commands in a split second)
19. You must know how to solve a problem in your mind or you cannot program the computer to do it for you.
20. You must learn to break down the solution to a problem that exists in your mind
    into small steps because remember the computer only does one thing at a time.
21. A good example is as follows:
    Look at 3 number and tell me the largest. Anyone can do this if you ask them to.
    But in writing a program to do this, you must be able to breakdown the little steps that your mind went through in solving the problem. You might say I just looked at the 3 numbers and spotted the largest and the rest is history.  To program the computer to solve this problem, you must be a whole lot more specific and detailed.
    FOR EXAMPLE:
    ... which number did you look at first
    ,,, is the first one looked at automatically the highest to start
    ... how is your mind comparing the numbers
    ... how do you know when to quit
    ... etc.
22. Remember that understanding variables are the key to programming and DO NOT FORGET that a variables can only hold one value at a time. That does not mean that a variable cannot be reused or added to etc. It just means that at any instant in time
    a variable will only have one specific value in it.
23. Remember that beginning programmers will normally be told what is their input for the program and what is expected as output.
24. In the above problem, a teacher might say:
    INPUT the 3 number one at a time, and find the largest  or
    he might say ASSIGN the 3 number to 3 different variables and go from there
    to find the largest.
25. You can see from this that a programmer must be aware of how the 3 numbers are going to get into the program for processing.
26. Next the programmer needs to know how to compare things (to find the largest)
    The program does not just look and it knows (like we think our mind does because
    we have done such a task millions of times)
27. An "if" statement is used by the programmer to compare things. It is really the same as the one that our mind uses in comparing things.
28. The "if" statement is an important control statement in all programming languages.
29. The "if" statement is what allows programs to make decisions and in the above example aren't we trying to decide which number is the largest.
30. To reiterate some important points:
    Data is assigned or input into variables
    Programs can compare the data that is in variables , knowing that a variable can only hold one value at a time, by using "if" statements.
31. One more important point to note here:  Programs refer to variables in all their
    commands. But remember that it is the data that is in the variable that is actually being referred to. Put another way, variables are symbolic names for data that has been put into the variable.
32. Some schools of thought will teach students to write programs by organizing their logic using different approaches --  flowcharting or breaking the  program down into smaller pieces. These approaches are right but I am taking this to a simpler level.
    We will analyze variables and commands to a point that we totally understand them -- then we can talk about organizing our logic according to a more sophisticated scheme.
33. Variables are what the program actually manipulates or plays with.
34. Variables will always be created with an exact purpose in mind.
35. If you do not know why you are creating a variable then you probably do not need it or you do not know the real nature of the problem or how to solve it.
36. Some variables will be reused by the programmer. They will take on a value by
    assignment or inputting and  after the commands have dealt with the variable (its value), THE VARIABLE CAN BE REUSED. Variables used for this purpose are normally associated with inputting data (from keyboard or file) into our program.
37. Other variables will take on values (usually by assignment) and these variables
    will not be reused because these values are to be maintained until the program has completed execution. Counters are good examples of these types.
38. Remember that when declaring or creating variables, use names easy to identify and make sure that the TYPE of variable your choose is appropriate for the values or data that it will contain.
39. I need to explain the following 5 commands before we can start writing programs:
    ... assignment statement
    ... input statements and output statements
    ... if statements
    ... do  while   statements
40. Assignment statements are use whenever you want to put a value directly into a variable.    SYNTAX is   variable = expression;
    Only one variable on the left of = sign. The = sign means "is assigned the value of".
    On the right of the = sign, you can have variables, constants, or a combination of these separated by arithmetic operators.
    e.g..   count = 0;                                      // used for comments  initialize count to 0
            total = num1 + num2;
            avg = (n1+n2+n3+n4)/4;
            counter = counter +1;                     // add 1 to counter
41. In the above notice how commands end in a semi colon and notice how comments are used to help describe the actions
42. I recommend that you declare all your variables at the top of the program, prior to|
    their usage. In that case the variable declarations listed below would precede the commands demonstrated in step 41 above.
    
       // declare all your variables at top of program
           int count;
           float n1,n2.n3.n4,avg;
           int num1,num2,total;
           int counter;
43. By the way variable names are made up of letters, numbers, and underscore character. Capital and small letters are allowed.
    EXAMPLES  
                   bb                                   // okay but too short for identification purposes
                   male_counter                                     // good name
                   counter_for_males_whoi_are_heavy     // okay but too much typing
44. INPUT and OUTPUT statements can take many forms in java but for simplicity
    I will use the          
                                System.out.print          // to print results to the screen
                                System.out.println        // print results to screen and 
                                                                     advance to the next line
                                File.read...                  // to input data or values from a file
             the ...  will be substituted by Int, Char, Float, UTF(string data)
45. Remember that when you are inputting data you normally input logical units
    not isolated characters or numbers. For example MARY not M and A and R and Y
    or 212 as someone's weight not 2 and 1 and 2. I think you see my point.
46. When inputting more than one thing in the input stream, a space normally is used to separate the logical units noted above.
47. The actual use of the 2 commands noted above for input and output will become obvious in the examples that follow.
48. IF statements are used for decision making within the program.
    A simple if statement takes the following form
          if ( condition)
           {
                  // any statements that you want to do if the condition is true
            }
              else
            {
                  // any statements that you want to do if the condition is false
             }
49. In the above example
    1...  the else is optional
    2...  the brackets can be deleted if you only want to do one statement
           in the block
    3...  the condition is any valid expression or comparison that can be
                evaluated to true or false
50. Condition normally involve relational symbols like > < ==  != etc. which stand for less than   greater than   equal to     not equal to. I think you imagine what some other might be.
51. Last I will describe the do  while  command sequence
          do
            {
                                            // in English -- perform the statements in the brackets
                                            // as long as the condition is true
    
            }
              while(condition);
52. All java programs have a weird set of statements called a shell. I will not deal with them because that will only confuse the issue. They are required   and most advanced programmers know their purpose. .

Understand all the examples that follow and you are on the way to programming

In order to show many examples and not confuse students with the
inputting of values from the keyboard or from a file, I will not get into some of the technical issues concerning input of data.  In all my examples I will use a 

file.read...  command.  Depending on the type of data being read, I will substitute a Chr, Int, Float, UTF ( for strings data )  in place of the ...   Therefore we can concentrate on logic development and not dwell on one slightly technical issue.