Monolithic programs is a bad idea, it just make things more complicated to you. As suggested in S3, making a function handling if a number is a prime or not will simplify the code.
for(x=2;x<y;++x)
a=y%x;
if(a==0) break;
Your code don't work, but I get your idea, the code is overkill, to check if 97 is a prime, it will check every number from 2 to 96. When you check by hand, do you stop at 96 or do you stop earlier?
The rule you apply to stop earlier should appear in you code.
The usage of
{}
matters in C, you should learn to use them as soon as possible.
Quote:
I mean (29-23-1)=5.
Are you sure the gap between 23 and 29 is 5 ?
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Your code do not behave the way you expect, or you don't understand why !
There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your code is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.
Debugger - Wikipedia, the free encyclopedia[
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Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[
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Basic Debugging with Visual Studio 2010 - YouTube[
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1.11 — Debugging your program (stepping and breakpoints) | Learn C++[
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The debugger is here to only show you what your code is doing and your task is to compare with what it should do.