Page 78 - The Unofficial Guide to Lego Mindstorms Robots

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Variables

To use a variable, you simply need to declare its name. Only integer variables are supported. Once a variable is declared, you
can assign the variable values and test it in the body of the program.
Here's a simple example:

int i;
task main() {
i = 0;
while (i < 10) {
PlaySound (0);
Wait(5 ∗ i);
i += 1;
}
}

This example beeps at successively longer intervals. The varia ble, i, is declared in the very first line:

int i;

Values are assigned to the variable usin g the = operator:

i = 0;

You can also assign input values to vari ables, like this (not part of the example):

i = SENSOR_2;

In the fo llowing line, one is added to the value in variable :
i

i++;

This is really shorthand for the following:

i += 1;

The += operator, in turn, is shorthand for this:

i = i + 1;

Using #define for Constants an d Macros

Constant values can be assigned meaningf ul names using #define. This is a idiom that will be familiar to C programmers.
He re is an example:

#define POWER 5
task main() {
SetPower(OUT_A + OUT_C, POWER);
On(OUT_A + OUT_C);
}

NQC replaces every occurrence of POWER with 5 in your source code before compiling it. Although this may not seem like a
big deal, it is; #define lets you create