INFINITY

If the implementation supports floating-point infinities, the macro INFINITY expands to constant expression of type float

If the implementation does not support floating-point infinities, the macro INFINITY expands to a positive value that is guaranteed to overflow a float

The style used to print an infinity is implementation defined.

Example

Show style used to print an infinity and IEEE format.

#include <stdio.h>
#include <math.h>
#include <stdint.h>
#include <inttypes.h>
#include <string.h>
 
int main(void)
{
    double f = INFINITY;
    uint64_t fn; memcpy(&fn, &f, sizeof f);
    printf("INFINITY:   %f %" PRIx64 "\n", f, fn);
}

INFINITY:   inf 7ff0000000000000

References