THE GENERAL LAYOUT


STRUCTURED PROGRAMMING
PRINCIPLES
STRUCTURING OF CONTROL FLOW AND COBOL
MODULAR PROGRAMMING AND COBOL
TOP-DOWN APPROACH AND COBOL
WEAKNESS AS STRUCTURED PROGRAMMING-COBOL
CONCLUSION





STRUCTURED PROGRAMMING


The precise meaning of the term structured programming depends on the interpretation given to it by the individual. It generally refers to a programming strategy that encompasses a number of methodologies to achieve certain objectives.IT MEANS THE WAY WE APPROACH to a particular problem to solve it.
this term was first used by e.w.dijkstra(1972).many other have worked in this field to expand its concept. It generally depends on the current market strategy and trends as what type of approach is to be made to a problem.today the hardware cost is minimum compared to previous days.thus there is a need to reduce personnel cost and there by reduce product cost.the reason for developing a program changes very soon. so we need to keep the old programs and see that they are modified properly to meet the needs .there by the time is saved.




PRINCIPLES

the general principles of a structured programming are as follows::
structuring of control flow.
decomposing a program into \'modules\' or \'partitions\'.\r\ntop down approach towards a programming design.\r\n \r\n \r\n \r\n STRUCTURING OF CONTROL FLOW\r\n \r\n \r\n Most of the times programs are highly complex systems of logic.the ability to design loop operations and taking different courses of action depending on a condition can make a program very complex.the large size of the program and inter connections between various parts through the transfer of control also increases the program \r\ncomplexity.thus to reduce this complexity the concept of structured programming was used.\r\n BOHM and JACOPINI and subsequently MILLS paved the way for restricted set of control structures.The following are the basic control structures :::\r\n\r\nSEQUENCE::-sequence of two or more instruction .\r\nIF-THEN-ELSE::-execution depending on condition\r\nDO-WHILE::-repetition of instruction as long as a condition is true.\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n It must be noted that the use of unconditional statement GO TO is not to be considered to be imperative statement to represent an operation.these basic structures can be combined to form various types of complex programs according to our needs.\r\n\r\nOne of the most important feature of a proper program(good program) is that there is only one entry and one exit. The main advantage of having a program like this is that we know where the program starts and where it \r\n",1]
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decomposing a program into 'modules' or 'partitions'.
top down approach towards a programming design.



STRUCTURING OF CONTROL FLOW


Most of the times programs are highly complex systems of logic.the ability to design loop operations and taking different courses of action depending on a condition can make a program very complex.the large size of the program and inter connections between various parts through the transfer of control also increases the program complexity.thus to reduce this complexity the concept of structured programming was used.
BOHM and JACOPINI and subsequently MILLS paved the way for restricted set of control structures.The following are the basic control structures :::
SEQUENCE::-sequence of two or more instruction .
IF-THEN-ELSE::-execution depending on condition
DO-WHILE::-repetition of instruction as long as a condition is true.























It must be noted that the use of unconditional statement GO TO is not to be considered to be imperative statement to represent an operation.these basic structures can be combined to form various types of complex programs according to our needs.
One of the most important feature of a proper program(good program) is that there is only one entry and one exit. The main advantage of having a program like this is that we know where the program starts and where it
\r\nThe basic advantage of a good program in comparison to conventional programs is that there is minimum use of GO TO..\r\nthe attention is not shifted which often makes programs difficult to understand.\r\n \r\n \r\n \r\n \r\nMODULAR PROGRAMMING\r\n \r\n \r\n \r\nMODULAR PROGRAMMING IS A STRATEGY WHERE A PROGRAM IS DECOMPOSED INTO A NUMBER OF IDENTIFIABLES OR MODULES.thus module is a portion of a program.A module itself can be decomposed further sub modules and so \r\non.Here the superior modules does not contain the codes of the modules it contains.The modules are in some else part of the program.Whenever necessary the superior module makes a call to that particular module and gets the \r\nresult.this activity ot the superior program is called "calling of a module".the module called is called is called "called module".\r\nThus there must be some facility to define and call the module.This facility is also available in COBOL as different paragraphs which are not exact modules but acts like module.COBOL also has the facility of sub programs.\r\n\r\nThe efficiency of a modular programming depends on how efficiently the modules are designed.the basic features of a module is:::\r\n\r\nthe module must perform a distinct function\r\nit may or may not return a value.\r\nit returns the control from wrere it was called.\r\nthe general advantages of using modules are::->>\r\n\r\nthey may be coded worked and tested separately\r\nerrors are easier to be found.\r\nit gives a logical approach to the program.\r\nfinally, it is useful when some modification has to be made in future due to requirement changes.",1]
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ends.thus all the statements till the exit is executed from the beginning.thus the attention is fixed on the logic.
The basic advantage of a good program in comparison to conventional programs is that there is minimum use of GO TO..
the attention is not shifted which often makes programs difficult to understand.




MODULAR PROGRAMMING



MODULAR PROGRAMMING IS A STRATEGY WHERE A PROGRAM IS DECOMPOSED INTO A NUMBER OF IDENTIFIABLES OR MODULES.thus module is a portion of a program.A module itself can be decomposed further sub modules and so on.Here the superior modules does not contain the codes of the modules it contains.The modules are in some else part of the program.Whenever necessary the superior module makes a call to that particular module and gets the result.this activity ot the superior program is called "calling of a module".the module called is called is called "called module".
Thus there must be some facility to define and call the module.This facility is also available in COBOL as different paragraphs which are not exact modules but acts like module.COBOL also has the facility of sub programs.
The efficiency of a modular programming depends on how efficiently the modules are designed.the basic features of a module is:::
the module must perform a distinct function
it may or may not return a value.
it returns the control from wrere it was called.
the general advantages of using modules are::->>
they may be coded worked and tested separately
errors are easier to be found.
it gives a logical approach to the program.
finally, it is useful when some modification has to be made in future due to requirement changes.
\r\n\r\n",0]
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