Increment and Decrement Operators (++, --)

These operators increment (add one to) or decrement (subtract one from) a variable. If they come before the variable, they return its new value; otherwise, they return its old value.

Some quick examples:

x++;  // adds one to x, and returns the old value of x
++x;  // adds one to x, and returns the new value of x

x--;   // decrement x by one and returns the old value of x
--x;   // decrement x by one and returns the new value of x

A more extended example:

x = 2;
y = ++x;      // x now contains 3, y contains 3
y = x--;      // x contains 2 again, y still contains 3

Warning

Be careful! You cannot put a space in between the two + or - signs. This example is broken:

// this line won't compile (notice the extra space):
int y = x+ +;

See Also

• Compound Arithmetic Operators (+= , -=, *=, /=)

License and Attribution

This documentation page was adapted from the Arduino Reference Documentation, which is released under a Creative Commons Attribution-ShareAlike 3.0 License.