imaginary - cppreference.com (original) (raw)
| | | | | ----------------------------- | | ----------- | | #define imaginary _Imaginary | | (since C99) |
This macro expands to the keyword _Imaginary.
This is a convenience macro that makes it possible to use float imaginary, double imaginary, and long double imaginary as an alternative way to write the three pure imaginary C types float _Imaginary, double _Imaginary, and long double _Imaginary
As with any pure imaginary number support in C, this macro is only defined if the imaginary numbers are supported.
| A compiler that defines __STDC_IEC_559_COMPLEX__ is not required to support imaginary numbers. POSIX recommends checking if the macro _Imaginary_I is defined to identify imaginary number support. | (since C99)(until C11) |
|---|---|
| Imaginary numbers are supported if __STDC_IEC_559_COMPLEX__ is defined. | (since C11) |
[edit] Notes
Programs are allowed to undefine and perhaps redefine the imaginary macro.
To date, only Oracle C compiler is known to have implemented imaginary types.
[edit] Example
#include <stdio.h> #include <complex.h> int main(void) { double imaginary i = -2.0*I; // pure imaginary double f = 1.0; // pure real double complex z = f + i; // complex number printf("z = %.1f%+.1fi\n", creal(z), cimag(z)); }
Output:
[edit] References
C17 standard (ISO/IEC 9899:2018):
7.3.1/5 imaginary (p: 136)
G.6/1 imaginary (p: 391-392)
C11 standard (ISO/IEC 9899:2011):
7.3.1/5 imaginary (p: 188)
G.6/1 imaginary (p: 537)
C99 standard (ISO/IEC 9899:1999):
7.3.1/3 imaginary (p: 170)
G.6/1 imaginary (p: 472)