# Rounding a number up to a Ceiling

In this lesson we will see how to write a custom function that gives the ceiling of a number.

You can download the stack for this lesson here: https://tinyurl.com/y7ebh6ez

**Update Note: In LiveCode 7.1 onwards, LiveCode has its own built-in "ceiling()" function. As such, the following lesson applies only to LiveCode versions earlier than 7.1.**

## Our custom function

We are going to write the function

`ceiling(pNumber)`

The function returns the ceiling of the given parameter pNumber. The ceiling of a number is the smallest following integer, more precisely ceiling(x) is the smallest integer not less than x.

The function will be called with a statement such as one of the following.

**put** ceiling(it) into field "Total Price"**
if** ceiling(field "Incident") > 4 **then** **go** **next** card

## Our example stack

For this lesson all we need is an entry field and a button to call the ceiling function and return the result.

## The ceiling function

The first thing the custom function must do is check that it has been passed a number, if the pNumber parameter passed to the function is not a number the function will return an error message.

The function's purpose is to produce the next higher number, or to "round up". We can't use the round function for this, because the round function rounds to the nearest integer, not necessarily to the next higher

e.g. `round(2.4)`

is 2, rather than 3

However, if we truncate the number(to get its integer part) and then add 1, we do get the desired result. By truncating 2.4 we get 2, add 1 and we get 3, the desired result.

Are we done? Not quite: there are two cases where this formula does not produce the ceiling number.

1 - If the number is already an integer, it is its own ceiling, so we don't want to add 1 to it.

2 - if the number is negative and not an integer, the above doesn't give us the ceiling. For example, the ceiling of -3.6 is -3, but truncating -3.6 gives -3, adding 1 gives us -2.

In both these cases the truncating gives us the ceiling of the number, without having to add 1.

## The trunc function

Luckily for us LiveCode has a built in **trunc** function which returns the integer part of a number so we can use it in our custom function.

**Examples: **

`trunc(33.567)`

*-- returns 33*

`trunc(-6.3)`

*-- returns -6*

## The script of the ceiling function

**function** ceiling pNumber**
## Check we have been passed a number**
if pNumber is not a number **then**
**return** "Error: not a number"**
end** **if**
**
## Check if the number is already an integer or is negative**
if pNumber < zero or pNumber is an integer **then**
## truncating gives the ceiling
return trunc(pNumber)**
else**
## truncate the number and add 1 to get the ceiling
return trunc(pNumber) + 1**
end** **if
end** ceiling

Can you tell me how I can format a field so that it only has 2 decimal places?

Thank You