# Left Shift and Right Shift Operators in C/C++

**Left Shift :**

**Denoted as : << **

**Data Structures in C**course to start learning today.

**Eg: N<<i (N: first operand, i: second operand)**

Takes two numbers, left shifts the bits of the first operand, the second operand decides the number of places to shift. Or in other words left shifting an integer “**x**” with an integer “**y**” denoted as ‘**(x<<y)’** is equivalent to multiplying **x** with **2^y** (2 raised to power y).

**eg:** lets take **N=22**; which is **00010110** in Binary Form.

Now, if “*N is left-shifted by 2*” i.e **N=N<<2** then **N** will become **N=N*(2^2)**. Thus, **N=22*(2^2)=88** which can be wriiten as **01011000.**

## C

`/* C++ Program to demonstrate use of left shift` ` ` `operator */` `#include<stdio.h>` `int` `main()` `{` ` ` `// a = 5(00000101), b = 9(00001001)` ` ` `unsigned ` `char` `a = 5, b = 9;` ` ` `// The result is 00001010` ` ` `printf` `(` `"a<<1 = %d\n"` `, a<<1);` ` ` ` ` `// The result is 00010010` ` ` `printf` `(` `"b<<1 = %d\n"` `, b<<1); ` ` ` `return` `0;` `}` |

## C++

`/* C++ Program to demonstrate use of left shift` ` ` `operator */` `#include <iostream>` `using` `namespace` `std;` `int` `main()` `{` ` ` `// a = 5(00000101), b = 9(00001001)` ` ` `unsigned ` `char` `a = 5, b = 9;` ` ` `// The result is 00001010` ` ` `cout <<` `"a<<1 = "` `<< (a<<1) << endl;` ` ` ` ` `// The result is 00010010` ` ` `cout <<` `"b<<1 = "` `<< (b<<1) << endl; ` ` ` `return` `0;` `}` `// This code is contributed by shivanisinghss2110` |

**Output**

a<<1 = 10 b<<1 = 18

**Right Shift :**

**Denoted as : >>**

**Eg: N>>i (N: first operand, i: second operand)**

Takes two numbers, right shifts the bits of the first operand, the second operand decides the number of places to shift. In other words right shifting an integer “**x**” with an integer “**y**” denoted as ‘**(x>>y)**‘ is equivalent to dividing x with 2^y.

**eg:** lets take **N=32**; which is **100000** in Binary Form.

Now, if “*N is right-shifted by 2*” **i.e N=N>>2** then **N** will become **N=N/(2^2)**. Thus, **N=32/(2^2)=8** which can be wriiten as **1000**.

## C++

`/* C++ Program to demonstrate use of right` ` ` `shift operator */` `#include <iostream>` `using` `namespace` `std;` `int` `main()` `{` ` ` `// a = 5(00000101), b = 9(00001001)` ` ` `unsigned ` `char` `a = 5, b = 9;` ` ` `// The result is 00000010` ` ` `cout <<` `"a>>1 = "` `<< (a >> 1)<< endl;` ` ` `// The result is 00000100` ` ` `cout <<` `"b>>1 = "` `<< (b >> 1) << endl;` ` ` `return` `0;` `}` `// This code is contributed by shivanisinghss2110` |

## C

`/* C++ Program to demonstrate use of right` ` ` `shift operator */` `#include <stdio.h>` `using` `namespace` `std;` `int` `main()` `{` ` ` `// a = 5(00000101), b = 9(00001001)` ` ` `unsigned ` `char` `a = 5, b = 9;` ` ` `// The result is 00000010` ` ` `printf` `(` `"a>>1 = %d\n"` `, a >> 1);` ` ` `// The result is 00000100` ` ` `printf` `(` `"b>>1 = %d\n"` `, b >> 1);` ` ` `return` `0;` `}` |

**Output**

a>>1 = 2 b>>1 = 4

**Important Points : **

- The left shift and right shift operators should not be used for negative numbers. The result of is undefined behaviour if any of the operands is a negative number. For example results of both -1 << 1 and 1 << -1 is undefined.
- If the number is shifted more than the size of integer, the behaviour is undefined. For example, 1 << 33 is undefined if integers are stored using 32 bits. For bit shift of larger values 1ULL<<62
**ULL**is used for Unsigned Long Long which is defined using 64 bits which can store large values. - The left-shift by 1 and right-shift by 1 are equivalent to the product of first term and 2 to the power given element(1<<3 = 1*pow(2,3)) and division of first term and second term raised to power 2 (1>>3 = 1/pow(2,3)) respectively.

As mentioned in point 1, it works only if numbers are positive.

## C++

`#include <iostream>` `using` `namespace` `std;` `int` `main()` `{` ` ` `int` `x = 19;` ` ` `unsigned ` `long` `long` `y = 19;` ` ` `cout <<` `"x << 1 = "` `<< (x << 1) << endl;` ` ` `cout <<` `"x >> 1 = "` `<< (x >> 1) << endl;` ` ` `// shift y by 61 bits left` ` ` `cout <<` `"y << 61 = "` `<< (y << 61) << endl;` ` ` `return` `0;` `}` `// this code is contributed by shivanisinghss2110` |

## C

`#include <stdio.h>` `int` `main()` `{` ` ` `int` `x = 19;` ` ` `unsigned ` `long` `long` `y = 19;` ` ` `printf` `(` `"x << 1 = %d\n"` `, x << 1);` ` ` `printf` `(` `"x >> 1 = %d\n"` `, x >> 1);` ` ` `// shift y by 61 bits left` ` ` `printf` `(` `"y << 61 = %lld\n"` `, y << 61);` ` ` `return` `0;` `}` |

**Output**

x << 1 = 38 x >> 1 = 9 y << 61 = 6917529027641081856

- The left-shift of 1 by i is equivalent to 2 raised to power i.

As mentioned in point 1, it works only if numbers are positive.

## C++

`#include <iostream>` `using` `namespace` `std;` `int` `main()` `{` ` ` `int` `i = 3; ` ` ` `cout <<` `"pow(2, "` `<< i << ` `") = "` `<< (1 << i) << endl;` ` ` `i = 4; ` ` ` `cout <<` `"pow(2, "` `<< i << ` `") = "` `<< (1 << i) << endl;` ` ` `return` `0;` `}` `// this code is contributed by shivanisinghss2110` |

## C

`#include<stdio.h>` `int` `main()` `{` ` ` `int` `i = 3; ` ` ` `printf` `(` `"pow(2, %d) = %d\n"` `, i, 1 << i);` ` ` `i = 4; ` ` ` `printf` `(` `"pow(2, %d) = %d\n"` `, i, 1 << i);` ` ` `return` `0;` `}` |

**Output**

pow(2, 3) = 8 pow(2, 4) = 16

Interesting Facts about Bitwise Operators in C