| Defined in header <complex.h> | ||||
|---|---|---|---|---|
| (since C99) |
The _Complex_I macro expands to a value of type const float _Complex with the value of the imaginary unit.
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 component.
Example
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | #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 2 | 1.0 + 2.0 * _Complex_I = 1.0+2.0i0.0 + -0.0 * _Complex_I = 0.0+0.0i |
References
- C11 standard (ISO/IEC 9899:2011):
- 7.3.1/4 _Complex_I (p: 188)
- C99 standard (ISO/IEC 9899:1999):
- 7.3.1/2 _Complex_I (p: 170)
See also
| (C99) | the imaginary unit constant i (macro constant) |
| (C99) | the complex or imaginary unit constant i (macro constant) |
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