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      ceil, ceilf, ceill

      From cppreference.com
      <c‎ |numeric‎ |math
       
       
       
      Common mathematical functions
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      Nearest integer floating-point
      ceil
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      Defined in header<math.h>
      float       ceilf(float arg);
      (1)(since C99)
      double      ceil(double arg);
      (2)
      longdouble ceill(longdouble arg);
      (3)(since C99)
      Defined in header<tgmath.h>
      #define ceil( arg )
      (4)(since C99)
      1-3) Computes the smallest integer value not less thanarg.
      4) Type-generic macro: Ifarg has typelongdouble,ceill is called. Otherwise, ifarg has integer type or the typedouble,ceil is called. Otherwise,ceilf is called.

      Contents

      [edit]Parameters

      arg - floating-point value

      [edit]Return value

      If no errors occur, the smallest integer value not less thanarg, that is⌈arg⌉, is returned.

      Return value
      math-ceil.svg
      Argument

      [edit]Error handling

      Errors are reported as specified inmath_errhandling.

      If the implementation supports IEEE floating-point arithmetic (IEC 60559):

      • The currentrounding mode has no effect.
      • Ifarg is ±∞, it is returned, unmodified.
      • Ifarg is ±0, it is returned, unmodified.
      • Ifarg is NaN, NaN is returned.

      [edit]Notes

      FE_INEXACT may be (but isn't required to be) raised when rounding a non-integer finite value.

      The largest representable floating-point values are exact integers in all standard floating-point formats, so this function never overflows on its own; however the result may overflow any integer type (includingintmax_t), when stored in an integer variable.

      This function (fordouble argument) behaves as if (except for the freedom to not raiseFE_INEXACT) implemented by

      #include <fenv.h>#include <math.h>#pragma STDC FENV_ACCESS ON double ceil(double x){double result;int save_round=fegetround();fesetround(FE_UPWARD);    result=rint(x);// or nearbyintfesetround(save_round);return result;}

      [edit]Example

      Run this code
      #include <math.h>#include <stdio.h> int main(void){printf("ceil(+2.4) = %+.1f\n", ceil(2.4));printf("ceil(-2.4) = %+.1f\n", ceil(-2.4));printf("ceil(-0.0) = %+.1f\n", ceil(-0.0));printf("ceil(-Inf) = %+f\n",   ceil(-INFINITY));}

      Possible output:

      ceil(+2.4) = +3.0ceil(-2.4) = -2.0ceil(-0.0) = -0.0ceil(-Inf) = -inf

      [edit]References

      • C23 standard (ISO/IEC 9899:2024):
      • 7.12.9.1 The ceil functions (p: TBD)
      • 7.25 Type-generic math <tgmath.h> (p: TBD)
      • F.10.6.1 The ceil functions (p: TBD)
      • C17 standard (ISO/IEC 9899:2018):
      • 7.12.9.1 The ceil functions (p: TBD)
      • 7.25 Type-generic math <tgmath.h> (p: TBD)
      • F.10.6.1 The ceil functions (p: TBD)
      • C11 standard (ISO/IEC 9899:2011):
      • 7.12.9.1 The ceil functions (p: 251)
      • 7.25 Type-generic math <tgmath.h> (p: 373-375)
      • F.10.6.1 The ceil functions (p: 526)
      • C99 standard (ISO/IEC 9899:1999):
      • 7.12.9.1 The ceil functions (p: 231-232)
      • 7.22 Type-generic math <tgmath.h> (p: 335-337)
      • F.9.6.1 The ceil functions (p: 462-463)
      • C89/C90 standard (ISO/IEC 9899:1990):
      • 4.5.6.1 The ceil function

      [edit]See also

      computes largest integer not greater than the given value
      (function)[edit]
      (C99)(C99)(C99)
      rounds to nearest integer not greater in magnitude than the given value
      (function)[edit]
      (C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
      rounds to nearest integer, rounding away from zero in halfway cases
      (function)[edit]
      rounds to an integer using current rounding mode
      (function)[edit]
      (C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
      rounds to an integer using current rounding mode with
      exception if the result differs
      (function)[edit]
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=c/numeric/math/ceil&oldid=172002"

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