COBOL FOR THE 21ST CENTURY PDF
Now in its 11th Edition, Nancy Stern, Robert Stern, and James Ley's COBOL for the 21st Century continues to show how to design COBOL programs that are. COBOL for the 21st Century. Nancy Stern. Hofstra University. Robert A. Stern. Nassau Community College. James P. Ley. University of Wisconsin-Stout. COBOL for the 21st Century. CHAPTER 1. AN INTRODUCTION TO STRUCTURED. PROGRAM DESIGN IN COBOL. CHAPTER OBJECTIVES. After completion.
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ebook author robert a stern created date am. cobol for the 21st century pdf by robert a stern ebook ebooks is available in digital. All orders for the regular 11th Edition will be automatically upgraded to the Update Edition. Please note the following changes made to the 11e Update Edition. NET. COBOL for the 21st century. A benchmark regarding reliability. NetCOBOL pixia-club.info was specifically developed for. Microsoft'pixia-club.info framework and.
Interactive vs. Batch Processing 1. An Overview of the Four Divisions 1. Definition of the Problem 1. Sample Interactive Program 1. Coding Rules 1. Sample Batch Program 1. Output Layout 1. The Program Illustrated 1. The Use of Periods 1. Our Definitions for Batch and Interactive Programs 1. Coding a Source Program 2. Coding Rules 2. The Main Body of a Program 2.
COBOL for the 21st Century
Optional Entries: Identification and Page and Serial Numbers 2. Column 7: Using Column 7 for Comments 2. Coding Rules for Areas A and B 2. Examples 2.
Overall Format 2. File-Name Rules 2. Implementor-Names or Device Specifications 2. Interactive and Batch Processing 3. Rules 3. Guidelines 3.
Use Meaningful Data-Names 3. An Overview 3. File Description Entries 3. Record Description Entries 3. Defining a Record 3.
Level Numbers 3. Types of Data Fields 3. Size of Data Fields 3. Format of PIC Clauses 3. Interactive Processing 3. Summary of Record Description Entries 3. Variable and Constant Data 3.
Types of Constants 3. Numeric Literal 3. Nonnumeric Literal 3. Figurative Constant 3. Introduction 3. Paragraphs that Serve as Modules 4. Defining Paragraphs 4. Rules for Forming Paragraph-Names 4. Statements within Paragraphs 4. The Sequence of Instructions in a Program 4. OPEN Statement 4.
The Instruction Format: A Review 4. A Structured Programming Technique 4. READ Statement 4. End-of-Job Processing: Programs Should Be Structured 5. Programs Should Be Modular 5. How Programs Are Designed 5. Pseudocode 5. The Four Logical Control Structures 5. Sequence 5.
Selection 5. Iteration 5. Case Structure 5. Example 1 5. Example 2 5. Code Each Clause on a Separate Line 5. Indent Clauses within a Statement 5. Syntax Errors 5. Logic Errors 5. Capturing Screen Displays in Interactive Processing 5.
Moving Integer Portions of Numeric Fields 6. Moving Decimal Portions of Numeric Fields 6. Moving Numeric Literals to Numeric Fields 6.
Moving Signed Numbers: An Introduction 6. Basic Rules 6. Qualification of Names 6. Performing Multiple Moves with a Single Statement 6. Reference Modification: Accessing Segments of a Field 6. Features of Printed Output and Screen Displays 6. Use of Edit Symbols 6. Spacing of Forms 6. Alignment of Information 6.
Solutions by Chapter
Printing Headings, Total Lines, and Footings 6. The Printer Spacing Chart 6. The Editing Function 6. Printing or Displaying Decimal Points 6. Suppressing Leading Zeros 6.
Printing or Displaying Dollar Signs and Commas 6. Printing or Displaying Plus or Minus Signs 6. Editing Using Floating Strings 6. FROM Statement 6. Advancing the Paper a Fixed Number of Lines 6. Advancing the Paper to a New Page 6. Printing Page Numbers 6. Printing or Displaying the Date of the Run 6.
The Y2K Problem 6. Printing or Displaying Quotation Marks 6. The Arithmetic Verbs and Intrinsic Functions 7. ADD Statement 7.
Basic Instruction Format 7. Examples of Arithmetic Operations 7. Determining the Size of Receiving Fields 7.
Basic Format 7. Order of Evaluation 7. Rules for Performing Arithmetic with Signed Numbers 7. Entering Signed Numbers 7. Calendar Functions 7. Statistical and Numerical Analysis Functions 7. Trigonometric Functions 7. Financial Functions 7. Character and String Functions 7. Basic Conditional Statements 8. Interpreting Instruction Formats 8. Coding Guidelines 8.
Indenting 8. Using Relational Operators in Place of Words 8. Planning Conditional Statements with Pseudocode 8. How Comparisons Are Performed 8. Nested Conditional 8. Compound Conditional 8. OR in a Compound Conditional 8. AND in a Compound Conditional 8.
COBOL for the 21st Century
Introduction 8. Order of Evaluation of Compound Conditionals 8. Order of Evaluation: Possibility 1 8. Possibility 2 8. Examples 8. Sign and Class Tests 8. Sign Test 8. Class Test 8. Negating Conditionals 8. Other programs tried to represent the year as This could cause a complete failure and cause date comparisons to produce incorrect results. Some embedded systems , making use of similar date logic, were expected to fail and cause utilities and other crucial infrastructure to fail.
While some commentators and experts argued that the coverage of the problem largely amounted to scaremongering ,  it was only the safe passing of the main " event horizon " itself, 1 January , that fully quelled public fears.
Some experts who argued that scaremongering was occurring, such as Ross Anderson , Professor of Security Engineering at the University of Cambridge Computer Laboratory , have since claimed that despite sending out hundreds of press releases about research results suggesting that the problem was not likely to be as big a problem as some had suggested, they were largely ignored by the media.
The need for bit conservation[ edit ] "I'm one of the culprits who created this problem. I used to write those programs back in the s and s, and was proud of the fact that I was able to squeeze a few elements of space out of my program by not having to put a 19 before the year. Back then, it was very important. We used to spend a lot of time running through various mathematical exercises before we started to write our programs so that they could be very clearly delimited with respect to space and the use of capacity.
It never entered our minds that those programs would have lasted for more than a few years. As a consequence, they are very poorly documented. If I were to go back and look at some of the programs I wrote 30 years ago, I would have one terribly difficult time working my way through step-by-step. Many tricks were used to squeeze needed data into fixed-field character records.
Saving two digits for every date field was significant in this effort. In the s, computer memory and mass storage were scarce and expensive. Early core memory cost one dollar per bit.
COBOL for the 21st Century, 11th Edition, Updated Edition
Programs often mimicked card processing techniques. Over time the punched cards were converted to magnetic tape and then disc files, but the structure of the data usually changed very little. Data was still input using punched cards until the mids. Machine architectures, programming languages and application designs were evolving rapidly. Neither managers nor programmers of that time expected their programs to remain in use for many decades. The realisation that databases were a new type of program with different characteristics had not yet come.
There were exceptions, of course. The first person known to publicly address this issue was Bob Bemer , who had noticed it in as a result of work on genealogical software. He spent the next twenty years trying to make programmers, IBM , the government of the United States and the ISO aware of the problem, with little result.
For example: The Microsoft Excel spreadsheet program had a very elementary Y2K problem: Excel in both Windows and Mac versions, when they are set to start at incorrectly set the year as a leap year for compatibility with Lotus This bug was fixed in later versions, but since the epoch of the Excel timestamp was set to the meaningless date of 0 January in previous versions, the year is still regarded as a leap year to maintain backward compatibility.
In the C programming language , the standard library function to extract the year from a timestamp returns the year minus Many programs using functions from C, such as Perl and Java , two programming languages widely used in web development, incorrectly treated this value as the last two digits of the year. In the Windows 3. An update was available. Some software, such as Math Blaster Episode I: In Search of Spot  which only treats years as two-digit values instead of four, will give a given year as "", "", and so on, depending on the last two digits of the present year.
Date bugs similar to Y2K[ edit ] Main article: Time formatting and storage bugs 4 January [ edit ] This date overflowed the bit field that had been used in the Decsystem 10 operating systems.
There were numerous problems and crashes related to this bug while an alternative format was developed. It was thus possible that database programs might act on the records containing unknown dates on that day.
Data entry operators commonly entered into required fields for an unknown future date, e. While fears arose that some programs might unexpectedly terminate on that date, the bug was more likely to confuse computer operators than machines. Main article: Zeller's congruence Normally, a year is a leap year if it is evenly divisible by four. A year divisible by , however, is not a leap year in the Gregorian calendar unless it is also divisible by For example, was a leap year, but , and were not.
Some programs may have relied on the oversimplified rule that a year divisible by four is a leap year. This method works fine for the year because it is a leap year , and will not become a problem until , when older legacy programs will likely have long since been replaced.
Other programs contained incorrect leap year logic, assuming for instance that no year divisible by could be a leap year. An assessment of this leap year problem including a number of real life code fragments appeared in Year problem[ edit ] Some systems had problems once the year rolled over to Both hexadecimal and BCD encode the numbers 0—9 as 0x0—0x9. But BCD encodes the number 10 as 0x10, whereas hexadecimal encodes the number 10 as 0x0A; 0x10 interpreted as a hexadecimal encoding represents the number Windows Mobile is the first software reported to have been affected by this glitch; in some cases WM6 changes the date of any incoming SMS message sent after 1 January from the year "" to "".
As a long integer in bit systems uses 64 bits, the problem does not realistically exist on bit systems that use the LP64 model.
Programming solutions[ edit ] Several very different approaches were used to solve the Year problem in legacy systems. Four of them follow: Date expansion Two-digit years were expanded to include the century becoming four-digit years in programs, files, and databases. This was considered the "purest" solution, resulting in unambiguous dates that are permanent and easy to maintain.
However, this method was costly, requiring massive testing and conversion efforts, and usually affecting entire systems. Date compression Dates can be compressed into binary bit numbers. This allows retention of data structure alignment , using an integer value for years.
Such a scheme is capable of representing different years; the exact scheme varies by the selection of epoch. Only input and output instructions for the date fields had to be modified, but most other date operations and whole record operations required no change.
This delays the eventual roll-over problem to the end of the year Windowing Two-digit years were retained, and programs determined the century value only when needed for particular functions, such as date comparisons and calculations. The century "window" refers to the year period to which a date belongs. This technique, which required installing small patches of code into programs, was simpler to test and implement than date expansion, thus much less costly.
While not a permanent solution, windowing fixes were usually designed to work for several decades. This was thought acceptable, as older legacy systems tend to eventually get replaced by newer technology. This freeware solution was one of the first downloadable solutions on the internet at the time and was found in one in four computers  and marketed through Planet City Software as Millennium Bug Compliance Kit.
Before [ edit ] On 28 December , 10, card swipe machines issued by HSBC and manufactured by Racal stopped processing credit and debit card transactions. Some programs were not active at that moment and problems would only show up when they were invoked. Not all problems recorded were directly linked to Y2K programming in a causality ; minor technological glitches occur on a regular basis.
Some caused erroneous results, some caused machines to stop working, some caused date errors, and two caused malfunctions. Reported problems include: In Sheffield , United Kingdom, incorrect risk assessments for Down syndrome were sent to pregnant women and two abortions were carried out as a direct result of a Y2K bug miscalculation of the mother's age.
Four babies with Down syndrome were also born to mothers who had been told they were in the low-risk group. The problem was fixed by and no services were disrupted. On 1 March [ edit ] Problems were reported but these were mostly minor. In Japan, data from weather bureau computers was corrupted. In the UK, railway self-service ticket machines "Quickfare" printed tickets bearing the date "00 JNR 00" for 3 months until mid March Sorting and Merging Updating an Indexed File Randomly Called Program Requirements AFTER Printing a Final Total Types of Constants 3.
Size of Data Fields 3.
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