_Complex_I - cppreference.com (original) (raw)

| | | | | ---------------------------------------- | | ----------- | | #define _Complex_I /* unspecified */ | | (since C99) |

The _Complex_I macro expands to a value of type const float _Complex with the value of the imaginary unit.

[edit] Notes

This macro may be used when I is not available, such as when it has been undefined by the application.

Unlike _Imaginary_I and CMPLX, use of this macro to construct a complex number may lose the sign of zero on the imaginary part.

[edit] Example

#include <stdio.h> #include <complex.h>   #undef I #define J _Complex_I // can be used to redefine I   int main(void) { // can be used to construct a complex number double complex z = 1.0 + 2.0 * _Complex_I; printf("1.0 + 2.0 * _Complex_I = %.1f%+.1fi\n", creal(z), cimag(z));   // sign of zero may not be preserved double complex z2 = 0.0 + -0.0 * _Complex_I; printf("0.0 + -0.0 * _Complex_I = %.1f%+.1fi\n", creal(z2), cimag(z2)); }

Possible output:

1.0 + 2.0 * _Complex_I = 1.0+2.0i 0.0 + -0.0 * _Complex_I = 0.0+0.0i

[edit] References

[edit] See also

| | the imaginary unit constant i (macro constant) [edit] | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | the complex or imaginary unit constant i (macro constant) [edit] |