# <<

## Description

The left shift operator << causes the bits of the left operand to be shifted left by the number of positions specified by the right operand.

## Syntax

variable << number_of_bits;

## Parameter Values

• variable: Allowed data types: byte, int, long.
• number_of_bits: a number that is < = 32. Allowed data types: int.

## Example Code

int a = 5; // binary: 0000000000000101 int b = a << 3; // binary: 0000000000101000, or 40 in decimal

※ NOTES AND WARNINGS:

When you shift a value x by y bits (x << y), the leftmost y bits in x are lost, literally shifted out of existence:

int x = 5; // binary: 0000000000000101 int y = 14; int result = x << y; // binary: 0100000000000000 - the first 1 in 101 was discarded

If you are certain that none of the ones in a value are being shifted into oblivion, a simple way to think of the left-shift operator is that it multiplies the left operand by 2 raised to the right operand power. For example, to generate powers of 2, the following expressions can be employed:

Operation Result --------- ------ 1 << 0 1 1 << 1 2 1 << 2 4 1 << 3 8 ... 1 << 8 256 1 << 9 512 1 << 10 1024 ...

The following example can be used to print out the value of a received byte to the serial monitor, using the left shift operator to move along the byte from bottom(LSB) to top (MSB), and print out its Binary value:

// Prints out Binary value (1 or 0) of byte void printOut1(int c) { for (int bits = 7; bits > -1; bits--) { // Compare bits 7-0 in byte if (c & (1 << bits)) { Serial.print("1"); } else { Serial.print("0"); } } }