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Postcondition loop and precondition loop

Programming in itself is quite complicated. To begin with, all actions should be spelled out step by step. But along with such a need, there are a number of possibilities that greatly facilitate the achievement of the task that programming should perform ("Pascal", "C", "Assembler" - no matter what language is used). One such tool is looping.

The importance of cycles in programming

postcondition loop




What is a cycle? Why is it necessary and what are the advantages a programmer gets when using it? The cycle is an important structural component of programming, which allows you to automate the execution of a certain series of actions, provided that the established parameters are observed. So, the simplest example of a loop is to bring a certain number to a power. There is no need to prescribe rows until it is enough, because the technique can do everything automatically with its help. In practical implementation, loops also save a lot of time and labor, since when using a loop, there is no need to register program code every time and for all actions. It is enough to introduce replaceable variables and run the implementation.But how is the loop structure built? Or even a few? There are quite a lot of options for implementing the cycle - we will consider information on a whole book about programming, Pascal or Assembler. Therefore, for purely educational purposes, we suggest analyzing the theoretical scheme of the two most popular in use:





  1. .
  2. .

, . . ? :

while «» do « »

pascal programming




This is a form of writing code when a loop statement with a postcondition for execution is after the body. At first glance it may seem strange: indeed, why put the circumstance of execution after the program code? But there is nothing strange here: the peculiarity of this form is that the code will be executed regardless of whether the execution conditions are met or not. But only 1 time. Then checks will follow, whether everything corresponds to how it should be, or not. And in the absence of proper conditions, the body of the cycle will be ignored. This is a very important and useful feature that the postcondition loop has. On the example of what it was told and where you can see the practical implementation of what is described here? Here is an example of a postcondition loop:





repeat

"Program code"

until "Condition"

General theoretical base of the cycle with a precondition

cycles with precondition and postcondition




But the most popular option is this one. Its peculiarity lies in the fact that execution of a condition requires fulfillment; without this, the code will never be executed. Usually the program code is very large-scale, and activation of it all will negatively affect the performance of the computer. Therefore, a rather tricky plan is used: most parts of the code are placed in loops or generally separate classes, which are accessed at precisely the right moments. The rest of the time this code is, but not used by the computer. This design saves processor power to run the program itself or other programs.

Practical implementation in various programming languages

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Conclusion

postcondition loop operator




So, summing up everything that has been written, we can say that a cycle with a postcondition or precondition allows you to conveniently save without losing quality. And when writing complex programs, he is one of the best friends of a programmer, helping him to make the code easier to execute and to read. Therefore, when writing your code, do not hesitate to use a cycle with a postcondition or precondition - they are created specifically to facilitate the process of creating software, and it will be a work against yourself - not to take this opportunity.



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