In C, ceil() rounds x up toward positive infinity. ceil(2.1) is 3, and ceil(-2.1) is -2, which is the next integer toward +infinity.
You pass one double. The result is still a double, such as 3.0, not an int. Include <math.h>.
Pass the number you want to round up. Start with this call.
ceil(2.1);| Call | What it does |
|---|---|
ceil(2.1) | Rounds up to 3. |
Include <math.h>. On GCC, link with -lm. The result type is still double.
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);| Parameter | Description |
|---|---|
| x | Required. The double to round toward +infinity. |
| Return Value | Description |
|---|---|
| double | The smallest integer value that is not less than x, stored as a double. |
Round a positive non-integer up to the next whole number.
#include <stdio.h>
#include <math.h>
int main(void) {
printf("%.1f\n", ceil(8.45));
printf("%.1f\n", ceil(8.0));
return 0;
}ceil.%.1f shows one decimal place.Toward +infinity means negatives move closer to zero when they have a fractional part.
#include <stdio.h>
#include <math.h>
int main(void) {
printf("ceil(-2.3) = %.1f\n", ceil(-2.3));
printf("floor(-2.3) = %.1f\n", floor(-2.3));
return 0;
}floor(-2.3) is -3.Convert an item count into how many full pages you need when each page holds a fixed size.
#include <stdio.h>
#include <math.h>
int main(void) {
int items = 25;
int per_page = 10;
int pages = (int)ceil(items / (double)per_page);
printf("pages = %d\n", pages);
return 0;
}25 / (double)10 is 2.5, not integer truncating division.ceil(2.5) is 3.0 so a partial page still counts.(int) is safe here because page counts are small.Compute cosine for angles measured in radians.
9 people found this page helpful