_status87, _statusfp

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Header File

float.h

Prototype

unsigned int _status87(void);
unsigned int _statusfp(void);

Description

Gets floating-point status.

_status87 gets the floating-point status word, which is a combination of the 80x87 status word and other conditions detected by the 80x87 exception handler.

_statusfp is identical to _status87 and is for Microsoft compatibility.

Return Value

The bits in the return value give the floating-point status. See float.h for a complete definition of the bits returned by _status87 and _status87.

Portability

	POSIX	ANSI C	ANSI C++	Win32	Win64	macOS
_status87				+
_statusfp				+

Example

#include <float.h>

/* Prints the status of the FPU */
void print_fp_status() {
	/* Obtain the FPU status word */
	int fp_status = _status87();
	printf("Status = %d", fp_status);

	/* Write the statuses */
	if (fp_status & SW_DENORMAL)
		printf(" denormalized");

	if (fp_status & SW_UNDERFLOW)
		printf(" underflow");

	if (fp_status & SW_INEXACT)
		printf(" inexact");

	printf("\n");
}

int _tmain(int argc, _TCHAR* argv[]) {
	double big_value = 1e-40;
	float short_value;

	/* Print the default status */
	print_fp_status();

	/* Force FP status change */
	short_value = big_value;
	print_fp_status();

	/* Clear FPU status word */
	_clear87();

	/* Force FP status change */
	big_value = short_value;
	print_fp_status();
}