C convert floating point to int

Question

I m using C  not C      I need to convert a float number into an int  I do not want to round to the the nearest number  I simply want to eliminate what is after the integer part  Something like  4 9 -  4 9 -  4

User · Answer

Good guestion  -- where I have not yet found a satisfying answer for my case  the answer I provide here works for me  but may not be future proof    If one uses gcc  clang   and have -Werror and -Wbad-function-cast defined  int val    int pow 10 9    will result  error  cast from function call of type  double  to non-matching type  int   -Werror bad-function-cast   for a good reason  overflow and where values are rounded needs to be thought out  EDIT  2020-08-30  So  my use case casting the value from function returning double to int  and chose pow   to represent that in place of a private function somewhere  Then I sidestepped thinking pow   more   See comments more why pow   used below could be problematic      After properly thought out  that parameters to pow   are good   int val   pow 10 9   seems to work with gcc 9 2 x86-64     but note  printf  quot  d n quot   pow 10 4     may output e g  -1121380856   did for me  where int i   pow 10 4   printf  quot  d n quot   i    printed 10000  in one particular case I tried

User · Answer

If you want to round it to lower  just cast it   float my float   42 8f  int my int  my int    int my float                gt  my int 42   For other purpose  if you want to round it to nearest  you can make a little function or a define like this    define FLOAT TO INT x    x  gt  0  int   x  0 5   int   x -0 5    float my float   42 8f  int my int  my int   FLOAT TO INT my float        gt  my int 43   Be careful  ideally you should verify float is between INT MIN and INT MAX before casting it

User · Answer

Use in C int C   var in float   They will convert implicit

User · Answer

double a   100 3  printf   f  d n   a   int  a  10 0     Output Cygwin 100 3 1003 Output MinGW  100 3 1002   Using  int  to convert double to int seems not to be fail-safe  You can find more about that here  Convert double to int

User · Answer

my var    int my var    As simple as that   Basically you don t need it if the variable is int

[c] C convert floating point to int

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