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author | Marti Bolivar <mbolivar@mit.edu> | 2010-10-20 06:46:52 -0400 |
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committer | Marti Bolivar <mbolivar@mit.edu> | 2010-10-20 06:46:52 -0400 |
commit | 22ff1db8a76c7047b61a424ae1fa5f43697fcb34 (patch) | |
tree | bf722c8a5a6bd40e0b33fc4a425e0e5b8b9f4216 /docs/source/arduino/for.rst | |
parent | bac6548fe90b0721e191d68df2677beb4b15f60a (diff) | |
download | librambutan-22ff1db8a76c7047b61a424ae1fa5f43697fcb34.tar.gz librambutan-22ff1db8a76c7047b61a424ae1fa5f43697fcb34.zip |
initial check-in of arduino docs in RST format (converted using wget+pandoc)
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diff --git a/docs/source/arduino/for.rst b/docs/source/arduino/for.rst new file mode 100644 index 0000000..b7e2e95 --- /dev/null +++ b/docs/source/arduino/for.rst @@ -0,0 +1,117 @@ +.. _arduino-for: + +for statements +============== + +Desciption +---------- + +The **for** statement is used to repeat a block of statements +enclosed in curly braces. An increment counter is usually used to +increment and terminate the loop. The **for** statement is useful +for any repetitive operation, and is often used in combination with +arrays to operate on collections of data/pins. + + + +There are three parts to the **for** loop header: + + + +``<strong>for</strong> (<strong>initialization</strong>;<strong> condition</strong>;<strong> increment</strong>) {`` + + + +``//statement(s);`` + + + +``}`` + +|image0| + + +The **initialization** happens first and exactly once. Each time +through the loop, the **condition** is tested; if it's true, the +statement block, and the **increment** is executed, then the +**condition** is tested again. When the **condition** becomes +false, the loop ends. + + + +Example +------- + +:: + + // Dim an LED using a PWM pin + int PWMpin = 10; // LED in series with 470 ohm resistor on pin 10 + + void setup() + { + // no setup needed + } + + void loop() + { + for (int i=0; i <= 255; i++){ + analogWrite(PWMpin, i); + delay(10); + } + } + + + +Coding Tips +----------- + +The C **for** loop is much more flexible than **for** loops found +in some other computer languages, including BASIC. Any or all of +the three header elements may be omitted, although the semicolons +are required. Also the statements for initialization, condition, +and increment can be any valid C statements with unrelated +variables, and use any C datatypes including floats. These types of +unusual **for** statements may provide solutions to some rare +programming problems. + + + +For example, using a multiplication in the increment line will +generate a logarithmic progression: + +:: + + for(int x = 2; x < 100; x = x * 1.5){ + println(x); + } + + + +Generates: 2,3,4,6,9,13,19,28,42,63,94 + + + +Another example, fade an LED up and down with one **for** loop: + + + +:: + + void loop() + { + int x = 1; + for (int i = 0; i > -1; i = i + x){ + analogWrite(PWMpin, i); + if (i = 255) x = -1; // switch direction at peak + delay(10); + } + } + + + +See also +-------- + + +- `while <http://arduino.cc/en/Reference/While>`_ + |