Floating Point Exception C Why and what is it

Question

I m building a program for the Euler projects question 3  and while that might not really matter as a result I m current trying to make this code take a number and test if it is prime or not  Now then before I get to troubleshoot the function it gives me the error  floating point exception  right after inputting the number  Here s the code   int main         int input      cout  lt  lt   Enter number     lt  lt  endl      cin gt  gt  input      int i   input 2      int c      for  i gt 0  i--             c  input i          if  c  0    i    1              cout  lt  lt   not prime   lt  lt  endl          else             cout  lt  lt   prime   lt  lt  endl            return 0      so essentially why is it giving me a floating point exception and what does that even mean

User · Accepted Answer

A  floating point number  is how computers usually represent numbers that are not integers -- basically  a number with a decimal point  In C   you declare them with float instead of int  A floating point exception is an error that occurs when you try to do something impossible with a floating point number  such as divide by zero

User · Answer

Since this page is the number 1 result for the google search  c   floating point exception   I want to add another thing that can cause such a problem  use of undefined variables

User · Answer

for  i gt 0  i--     is probably wrong and should be  for    i gt 0  i--    instead  Note where I put the semicolons  The condition goes in the middle  not at the start

User · Answer

Problem is in the for loop in the code snippet      for  i   0  i--    Here  your intention seems to be entering the loop if  i   0  and  decrement the value of i by one after the completion of for loop   Does it work like that  lets see   Look at the for   loop syntax     for   initialization  condition check  increment decrement           statements          Initialization gets executed only once in the beginning of the loop   Pay close attention to     in your code snippet and map it with for loop syntax   Initialization   i   0   Gets executed only once  Doesn t have any impact in your code   Condition check   i --   post decrement                 Here  i is used for condition check and then it is decremented                 Decremented value will be used in statements within for loop                 This condition check is working as increment decrement too in your code     Lets stop here and see floating point exception     what is it  One easy example is Divide by 0  Same is happening with your code      When i reaches 1 in condition check  condition check validates to be true  Because of post decrement i will be 0 when it enters for loop     Modulo operation at line  9 results in divide by zero operation      With this background you should be able to fix the problem in for loop

User · Answer

Lots of reasons for a floating point exception   Looking at your code your for loop seems to be a bit  incorrect    Looks like a possible division by zero   for  i gt 0  i--    c  input i    Thats division by zero at some point since you are decrementing i

[c++] Floating Point Exception C++ Why and what is it?

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