# Native Expressions in Construct 2

### Operators

You can use the following operators in expressions:

**+** (addition)**-** (subtraction)***** (multiplication)**/** (division)**%** (modulo, remainder after division)**^** (raise to power, e.g. *5 ^ 2 = 25*)**&** (build strings, e.g. *"Your score is: " & score*)

There are also comparison operators **=**, **<>**, **<**, **<=**, **>**, **>=** for comparing values. They return 1 if the comparison is true or 0 if false.

& also doubles as logical AND, and **|** is a logical OR operator. These are useful combined with the comparison operators, e.g. *score < 0 | health < 0*, which also return 1 if true and 0 if false.

**?:** is a *conditional* operator, which allows you to test conditions in expressions. This is especially useful when used with the comparison operators and logical operators. It takes the form *condition ? result_if_true : result_if_false*

e.g. *health < 0 | score < 0 ? "Game over!" : "Keep going!"*.

The condition counts as true if it is non-zero, and false if it is zero.

### Strings (text)

Text is also known as *strings* in programming, and Construct 2 also sometimes uses this naming convention. Text in expressions should be surrounded by double-quotes, e.g. *"Hello"*

The double-quotes are not included as part of the text, so setting a text object to show the expression *"Hello"* will make it show *Hello*, without any double-quotes. To include a double-quote in a string, use two double-quotes next to each other (""), e.g. *"He said ""hi"" to me"* will return *He said "hi" to me*.

You can use **&** to build strings out of mixed text and numbers, e.g. *"Your score is: " & score*

### Standard Mathematical Expressions

The full list of expressions can be found in Construct 2 itself: double-click the *System* object in the floating expressions panel when you're typing in an expression. However, some common ones are listed here.

**sin** (sine of an angle in degrees)**cos** (cosine of an angle in degrees)**tan** (tangent of an angle in degrees)**asin** (inverse sine, returns degrees)**acos** (inverse cosine, returns degrees)**atan** (inverse tangent, returns degrees)**sqrt** (square root)**abs** (absolute value)**exp** (exponent, e^x)**ln** (logarithm to base e)**log10** (logarithm to base 10)

It's worth remembering Construct 2 always uses degrees, never radians. If you need to enter an angle anywhere in Construct 2, it will be in degrees.

### Conversion Expressions

**int(x)** - convert x to integer**float(x)** - convert x to float**str(x)** - convert x to string

Don't forget you can use & to build strings, e.g. *"Your score: " & score* returns "Your score: 10" as a string if score is 10.

### Other Expressions

**Angle(x1, y1, x2, y2)** - Returns the angle, in degrees, between the points (x1, y1) and (x2, y2), using atan2(y2 - y1, x2 - x1).

**Ceil(number)** - Round a number up (eg. ceil(6.1) returns 7).

**Distance(x1, y1, x2, y2)** - Returns the distance between the points (x1, y1) and (x2, y2).

**dt** - Delta-time. See Delta-time and framerate independence.

**Floor(number)** - Round a number down (eg. floor(6.7) returns 6).

**fps** - Current framerate in frames per second.

**len(x)** - return length of the string x

**Lerp(a, b, x)** - Linear interpolation: Calculates a + x(b - a), or linearly interpolates a to b by x%. Eg. lerp(a, b, 0.25) gives the value 25% of the way from a to b

**LoopIndex** - Current (top-level) loop index

**LoopIndex("name")** - Loop index of a loop of given name

**ObjectCount** - Total number of object instances in the game.

**Max(a, b [,c,...])** - Retrieve the maximum of the given values. You can pass any number of values

**Min(a, b [,c,...])** - Retrieve the minimum of the given values. You can pass any number of values

**Newline** - text string containing a line break character, e.g. *"Hello" & newline & "World"*

**Random(N)** - Returns a random number between 0 and N, not including N. The result includes fractions, so *random(3)* can return 2.5. Use *floor(random(n))* to generate a random whole number up to but not including N, e.g. *floor(random(3))** will return either 0, 1 or 2. Random(A, B) can also be used to generate a random number between A and B.

**Round(value)** - Rounds value to its nearest whole number, eg. Round(6.8) gives 7

**Scrollx, Scrolly** - Current scroll position

**Timescale** - The current time scale. See Delta-time and framerate independence.

**Time** - Time in seconds since the game started.

**TickCount** - Number of ticks elapsed since the game started.

Don't forget to check the expressions panel in Construct 2 for the full list.

### Useful expressions in other objects

Both the Mouse and Touch objects allow you to pass a layer parameter for the X and Y expressions. This is very useful if you scale or rotate layers.

e.g. **Mouse.X("Layer 1")** returns the mouse's X position on Layer 1, taking in to account its parallax, scale and angle. If you use only Mouse.X, it does not take in to account parallax, scale or angle, so the result can be wrong.

### Object indexing in expressions

You can add a 0-based object index to get expressions from different object instances.

e.g. **Sprite(0).X** gets the first Sprite instance's X position, and **Sprite(1).X** gets the second instance's X position. You can also pass another expression for the index. Negative numbers start from the opposite end, so **Sprite(-1).X** gets the last Sprite's X position.

This can be applied to any object expression, not just Sprites.

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## Comments

Great reference for the expressions!

You should add the "distance" expression, very useful!

distance(Obj1.X, Obj1.Y, Obj2.X, Obj2.Y)

Some of the info was out of date since that forum post you had linked to so I made a few edits, hope you don't mind!

Added some quotes for named loops.

loopindex("a") rather than loopindex(a)

Really useful guide, I was trying to work out how to do carriage returns - turns out the function was there all the time... "newline" :)

This is a great start - thank you.

Consider adding coverage of magic keywords like "words", "chars", and how they relate to "At", "Count", "CurValue", "CurX, Y, Z", "Depth", "Height", "Width", "UID" would also be helpful.

I am trying to make a word game and probably didn't need to insert delimiters into the content strings if I can get word and char counts in a 2D loop without them.

Oh thank god, I've been looking for these!

This is gold :)

Thanks, I have no knowledge about this stuff and this way I can alway take peek when needed.

Hey thanks pearsonlands; I was a little rusty on my coding and I couldn't remember how to mix fixed text and variables in a score readout; After reading thru the tut here, I got everything up and running fine.

Nice tutorial, but we need some string functions to decompose some string...

Wow, i never knew I could use comparison and && or || in an expression, this changes everything! Thx

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## Leave a comment

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Very helpful tutorial! Especially for those of us who are not maths geniuses ;)