THE AUTOMATED FLOWCHART DESIGN AND CODE WRITING SYSTEM

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COMPUTER PROGRAMMING AND PROGRAM PROBLEM SOLUTION

I have listed some sample program problem and their algorithmic solution illustrated with flowchart. I also have the source code that is generated from these flowchart by LogicCoder. The information here is available in pdf format along with actual flowchart files that you can use with LogicCoder.

WHAT IS A COMPUTER?

A consise definition of a computer is as follows:
Any machine or device that will accept an input amount of data, process it under the control and direction of a program and then output the process result to some other device or medium. Hence, a computer is made out of the basic elements illustrated here.

DIGITAL COMPUTERS AND THE STORED PROGRAM CONCEPT

A microcomputer system is made out of three basic functional elements:
1. Input and Output (I/O) ports
2. A Central Processing Unit (CPU) and
3. Main Memory

Each component of a microcomputer system can in turn be broken down into smaller sub-system components. For example, the CPU (or microprocessor) consists of the following sub-system components:
(1) A set of registers
(2) A control unit
(3) An arithmetic and logic unit (ALU).

The operations performed by a computer require data. Data values are represented as digital signals like that illustrated in figure 1-3. Data is the representation of facts, concepts, or instructions in a structured and logical manner suitable for processing, communication, and interpretation by humans or some programmed device. Examples of data are: The balance of a bank account, The score a student receive on a test, or The list of all male students doing a particular subject at a college. The purpose of a computer is to accept and process data to produce useful information for human use. In the context of a digital computer system, we define data as Information in a form that can be used by a computer program.

The numeric characters "1" and "0" are used to represent numbers in the Binary Number system. We use the shotened expression "Bit" when refering to these numeric digits in base 2. The Binary number system uses the principle of place value positions to represent numeric values.

The place value of each bit position in a seven bit binary number, starting at your right and moving to the left are as illustrated by the example in figure 9-36.

Each character on a standard computer keyboard is encoded in a binary system so that the digital compputer can use the information that it represents in a logical and consistent manner. For example, the character "1" has a ASCII coded value assigned to it in this system of coding. The coded value has a decimal equivalent as illustrated here.

Therefore, we see that the signal represented in figure 1-3 could be that of the ASCII code for a keyboard character. It could even be that of a coded machine instruction been transmiited through the system or it could be the representation of some othere data format been used by a program.

WHAT IS A COMPUTER PROGRAM?

A computer program is a predetermine sequence of instructions that specify the operations to be done by a computer on data values. An instruction is a sequence of Binary Digits (bits) that can be used to control the internal electronics of a digital computer system. Therefore, instructions are machine codes that specify what operation is to be performed by the electronics of the computer system.

The "Stored Programming Concept" requires that both th data values and the instructions that controls operations on them during the run of a program to be represented in a digital format and be stored in the Internal memory of the computer system.

WHAT IS A PROGRAMMING LANGUAGE?

Assembly language is machine language written using mnemonics. A mnemonic is a word or combination of letters that suggest the meaning of the instruction it represents. Like BASIC, an assembly language consists of a set of commands that can be written into instructions that tells the computer what to do. However, each mnemonic word in an Assembly Language instruction set refers directly to the digital components of the computer system. Therefore, we see that Assembly Language mainly provides a convenient abstraction of the binary interpretation of a particular machine instruction set and the representation of data values on the system. Assembly Language does not adequately abstract the structure of a system.

From this we see that a programming language forms an interface between the programmer and the hardware system of the computer. There are levels of abstraction between the hardware system and the programming language. These abstractions are logical and are built on consistent rules that manifest themselves at the software interface as syntax and semantic rules in particular programming languages. Good programmers have a comprehensive knowledge of the way digital computer systems works and is able to appreciate the syntax and semantic rules in well defined programming languages. Understanding of a computer system includes basic knowledge of the way the hardware system works at machine or assembly language level.

Click the following link to purchase books with the above and following information with more deatiled explanation. Click HERE More information about these books can be found at this link.

HIGH LEVEL PROGRAMMING LANGUAGES

A digital computer system is design to execute instructions coded in a digital format. The set of instructions that the computer system is design to execute is called the machine instruction set for the system. Programming a computer system at machine level requires that the programmer is familiar with the instruction set of the machine and the physical architectiure of the system. Therefore, as you can appreciate, people who are not expert in digital system are easily put off at this level.

Therefore, we had to invent a system whereby a person who is not an expert at this level can program such a digital device that will solve a problem for the programmere with the solution approach been in the programmer's problem domain as opposed to that of the implementation machine domain.

In a high level programming language instructions are written using statements and expressions similar to those used in every day natural languages. Instructions written in a low-level language are written using machine code or mnemonics. Low level languages are machine oriented. Because of the limitation of low level programming languages, high level languages were developed. High level languages are:
(a) Similar to English with the usage of words and symbols
(b) More user friendly than low level languages
(c) Problem oriented rather than machine oriented
(d) Shorter than their machine equivalent.
A single statement in a high level language can be translated into many machine instructions

A SYSTEMATIC APPROACH TO PROGRAMMING

Click the following link to get more information about the systematic approach to programming and the Program Development Life Cycle. Click HERE

WHY USE PROGRAM FLOWCHARTS?

Because program flowcharting is a visual system that helps you to seperate the issues of a program language paradigmn from those of the control logic in a prograam solution.

This section gives a concise introduction to the concepts and principles of flowcharting as a means for illustrating program algorithms to be executed on digital computer systems. This on-line documentation is not intended to be a detailed practical guide. Reference sources that gives more practical learning material including programming language concepts and design techniques are given at the link to additional learning resources. I will give you a link that gives you some experimental results from students learning programming with a visual design system as opposed to purely using a text base programming language.

The difference with UML is that it is base on high level concepts that are not well defined and does not deal with issues that have been bugging software engineers and computer programming for a long time now. Typical issues UML fail to deal with are the issue of Complexity, Maintainability and Re-usability. LogicCoder effectively deals with these issues by developing a standard for the design of program algorithms with the use of program flowchart. These are simple straight forward easy to understand principles. They are not targetted at the highly academic but they can be used by the highly creative person to build sound, large, complex and consistent systems.

Visual programming system that autoamates a lot of programming task for the development of compplex software systems is evolving and is becoming predominant choice in all areas of program/software development.

SAMPLE PROGRAM PROBLEMS AND THEIR SOLUTION FLOWCHART

The sample program used in this chapter prepares a report on a checking account. The report is an output listing of checks drawn on a personal account in the month of September. Each line of the report list information on each check drawn during the month as follows. The amount drawn on each check, the check number, the check date and the person to whom the check is made payable. At the end of the report listing, the total number of checks and the total amount drawn on all checks for the month are printed on the output report.

void main(void)
{
r = 0; TotalChecks = 0;TotalAmount = 0;
printf("\n\nChecking Account report\t Date: %s", __DATE__);
scanf("%s,%f,%s",FileRec[r].Name, &FileRec[r].Amount, FileRec[r].Payee);
while(strcmp(NAME, "END OF FILE"))
{
TotalChecks++;
TotalAmount += CheckFile[r].Amount;
printf("\n\t%s\t%.2f\t%s", FileRec[r].Name, FileRec[r].Amount, FileRec[r].Payee);
scanf("%s,%f,%s",FileRec[r].Name, &FileRec[r].Amount, FileRec[r].Payee);
}
printf("\n\n\tTotal number of checks %d", Totalchecks);
printf("\nTotalAmount of all checks: %s", TotalAmount);
}

ANOTHER PROGRAM SPECIFICATION

Click the following link to download a sample free tutorial copy of LogicCoder with the source code text file for the following flowchart. Download is a zipfile for Ms Windows. Click to dowwnload. When you have installed LogicCoder, load the flowchart below and then the source code text file. You can then generate the required C/C++ program. You can then do modifications to the flowchart to create other programs with similar control logic.

A mileage report for sales people is to be prepared. The input test data is listed below. Each report line should contain the sales person's name, the beginning mileage, the ending mileage, the total mileage done (ending mileage - beginning mileage), and the mileage allowance. The mileage allowance is calculated by multiplying the total mileage by 0.20. The total number of sales persons, the total mileage done by all sales persons, and the total mileage allowance for all sales persons is to be printed at the end of the listing. The output listing should contain report and column headings

A sample copy of input test data is given in the table below. The input test data is to be included as part of the source code.

ANOTHER PROGRAM SPECIFICATION

Our next sample program problem illustrate the basic elements in the control logic of the of the Case structure and its implementation within the loop logic structure.You can also have control logic for a loop nested on either legs of the Case logic structure.

The case structure can also have multiple instructions on either or both path that is given control after the decision instruction is executed. Figure 4-3 illustrates an example of this.

A traffic citation report is to be prepared. You are required to design and code a program that will produce the report. INPUT DATA FILE The input test data file consists of records. Each record contain the name of the person receiving the traffic citation, a code that indicate whether the citation is for moving (code M) or for non-moving (code N) violation, and the number of citation for that person over the pass three years. The input test data is given in the table below.

Click the following link to get sample download of LogicCoder flowchart files.

Here is another sample program problem in which an algorithm is required that scan through a data file consisting of records in order to determine the largest and the smallest in a selected fild. In this case, the program problem is specific as you can determine from the specification given. However, the problem belong to a class of well known or common problem. Therefore, a generalise or generic algorithm would be useful for impleenting a solution.

If you were to use LogicCoder to derive a solution to this problem, you could use this single solution to generate the required generic algorithm. In LogicCoder, we call a flowchart that represent a generic algorithm a "Template flowchart". You can use a template flowchart to quickly implement the solution to any problem that belong to the class of problems represented by the generic algorithm.

A program is to be designed and then coded in BASIC that will produce a wheat production listing. Each input record used in the data file contain the field number from which the wheat is harvested, and the tonnage of wheat produced. The following information should be listed at the end of the report: The total tonnage of wheat produced from all fields, The field number and tonnage of the field that produce the most wheat, The field number and tonnage of the field that produce the least wheat. The input test data is given below.

Notice from this program logic design that you are basically selecting the maximum and the minimum values from a set of values. Therefore, the instance of this program algorithm implement the solution of a more general problem, i.e. selection of the maximum and the minimum from a set of values. This gives us the opportunity to create what we call a "GENERIC SOLUTION" for this class of problems. LogicCoder allow you to create generic solutions to class of programming problems by creating a "Template flowchart" from a given instance within that class of problems. You can then use the template flowchart to implement a solution to any problem within the class of problems. You can also creat template flowchart base solely on a visual perception in the control logic presented in a flowchart. Therefore, you can have template for class of problems that has similar processing pattern requirement.

ANOTHER SAMPLE PROGRAM SPECIFICATION

With LogicCoder, you can easily transfer the implementation of your program logic design from a given source language to another with very little effort. You do this by paying more attention to the control logic of your program and the meaning of command statements in the source language. No more need for "hang-ups" on programming lnguage paradigms.

500 REM ****** PROCESSING ******
510 REM
520 PRINT TAB(11) "DESERT PARK"
530 PRINT " "
540 PRINT " NAME RESIDENCY DAYS FEES "
550 PRINT " "
560 REM
570 READ N$, C$, D
580 REM
590 IF N$ = "END OF FILE" THEN 850
600 IF C$ = "R" THEN 700
610 IF C$ = "N" THEN 650
620 PRINT USING F1$; N$, U$
630 GOTO 810
640 REM
650 LET A = D * C3
660 LET T2 = T2 + A
670 PRINT USING F1$; N$, O$, D, A
680 GOTO 800
690 REM
700 IF D > D1 THEN 740
710 LET A = D * C1
720 GOTO 770
730 REM
740 LET A = (D1*C1) + ((D-D1)*C2)
750 GOTO 770
760 REM
770 LET T2 = T2 + A
780 PRINT USING F1$; N$, R$, D, A
790 GOTO 810
800 REM
810 LET T1 = T1 + 1
820 READ N$, C$, D
830 GOTO 590
840 REM
850 PRINT " "
860 PRINT USING F2$; T1
870 PRINT USING F3$; T2
880 END

More advance versions of LogicCoder allow you to select to generate BASIC programs with the use of standard control structures as opposed to that that uses the traditional line numbering as illustrated here. Many high level programming languages implement these standard control structures with the use of standard control statements such as do-while, while, if, if-then and so on. Never the less, as we have seen, with LogicCoder there is no need to think about these control staements when writing the source code for a program.

Click the following link to download a copy of this flowchart and the C/C++ source code text file.

ANOTHER PROGRAM SPECIFICATION

If the merge algorithm is such that it keeps the indices of a sequence of equal values from a given list in sorted order. I.e. they are kept in the same order as they were before the merge as illustrated in the output example for the above input, the algorithm is said to be stable. Otherwise, the algorithm is said to be unstable. Output when the merge operation is stable is as illustrated by C in figure 3-15. The encoding algorithm should encode the sequence in which the values in C are selected as follows: 10011100110100.

Note that, the merge operation that produces the output list C selects values from A in preference to that from B whenever a tie occurs. We define stability in the general sense to mean that values from A are always given preference whenever a tie occurs between values in A and B and that the indices of equal set of values are kept in sorted order at the end of the merge operation.

During the merge if there is a tie between a value from the A list and the B list, the value from the A list is given preference to that from the B list.

The overall control logic to be used in the program design is relatively simple and straightforward as illustrated by the flowchart in figure 3-16. However there is a need for the use of several bit-manipulating functions in order to meet the overall program objective.

For the purpose of doing a visual checks on the results of our program, we define a function that will print the bit pattern for a value stored as an unsigned long int. We call this function Print_bits( ). In this function we select each bit in the value to be printed by shifting it to the LSB position and then masking out the remaining bits. This function is defined in the source code of figure 3-17.

Figure 3-20
The source code that implements the program logic illustrated by the flowchart in figure 3-16.

Further information on this program problem is found in the text book "STRUCTURED PROGRAMMING WITH ANSI C" Page 15 - 17

void main(void)
{
unsigned int Bit_counter = i = j = 0;
while((i < 12)&&(j < 12))
{
if(Array1[i] <= Array2[j])
{
Coded_bits = Coded_bits |Set_bit(Coded_bits, Bit_counter, 1);
i++;
}
else
{
Coded_bits = Coded_bits |Set_bit(Coded_bits, Bit_counter, 0);
j++;
}
Bit_counter++;
}
if(j == 12)
Set_bit(Coded_bits, Bit_counter, 1);
Print_bits(Coded_bits); }

Most information listed on this web page are taken from the following text books
(1) STRUCTURED PROGRAMMING WITH BASIC, Vol. 1, ISBN 0-9544270-1-7; Price $44.00 USD
(2) STRUCTURED PROGRAMMING WITH ANSI C; ISBN 0-9544270-0-9; Price $56.00 USD
You receive a free tutorial version of LogicCoder for ANSI C and BASIC with any purchase.