C Math nextafter() Function
Example
Get the next double value after 1.0:
double x = nextafter(1.0, 2.0);
if (x > 1.0) {
printf("x is a little bigger than 1");
}Definition and Usage
The nextafter() function returns the closest floating point number to x in the direction of y. If x and y are equal, it returns y.
A double cannot store every decimal number, so there is a small gap between two double values that follow each other. In the example, x is the first double after 1.0. It is so close to 1.0 that printf() prints it as 1.000000, but x > 1.0 is true.
The nextafter() function is defined in the <math.h> header file.
Tip: nexttoward() does the same, but y is a long double.
Syntax
double nextafter(double x, double y);There are also versions for float and long double values: nextafterf() and nextafterl().
Parameter Values
| Parameter | Description |
|---|---|
| x | Required. The number to start from. |
| y | Required. The direction to go in. If y is bigger than x, the result is bigger than x. |
Technical Details
| Returns: | A double value with the closest number to x in the direction of y. |
|---|
Related Pages
Read more about math in our C Math Tutorial.
