## Python | Print all the common elements of two lists

Given two lists, print all the common elements of two lists.

**Examples:**

Input : list1 = [1, 2, 3, 4, 5] list2 = [5, 6, 7, 8, 9] Output : {5} Explanation: The common elements of both the lists are 3 and 4 Input : list1 = [1, 2, 3, 4, 5] list2 = [6, 7, 8, 9] Output : No common elements Explanation: They do not have any elements in common in between them

**Method 1:Using Set’s & property**

Convert the lists to sets and then print **set1&set2**. set1&set2 returns the common elements set, where set1 is the list1 and set2 is the list2.

*Below is the Python3 implementation of the above approach: *

- Python3

`# Python program to find the common elements` `# in two lists` `def` `common_member(a, b):` ` ` `a_set ` `=` `set` `(a)` ` ` `b_set ` `=` `set` `(b)` ` ` `if` `(a_set & b_set):` ` ` `print` `(a_set & b_set)` ` ` `else` `:` ` ` `print` `(` `"No common elements"` `)` ` ` ` ` `a ` `=` `[` `1` `, ` `2` `, ` `3` `, ` `4` `, ` `5` `]` `b ` `=` `[` `5` `, ` `6` `, ` `7` `, ` `8` `, ` `9` `]` `common_member(a, b)` ` ` `a ` `=` `[` `1` `, ` `2` `, ` `3` `, ` `4` `, ` `5` `]` `b ` `=` `[` `6` `, ` `7` `, ` `8` `, ` `9` `]` `common_member(a, b)` |

**Output:**

{5} No common elements

**Method 2:Using Set’s intersection property**

Convert the list to set by conversion. Use the intersection function to check if both sets have any elements in common. If they have many elements in common, then print the intersection of both sets.

Below is the Python3 implementation of the above approach:

- Python3

`# Python program to find common elements in` `# both sets using intersection function in` `# sets` `# function` `def` `common_member(a, b): ` ` ` `a_set ` `=` `set` `(a)` ` ` `b_set ` `=` `set` `(b)` ` ` ` ` `# check length` ` ` `if` `len` `(a_set.intersection(b_set)) > ` `0` `:` ` ` `return` `(a_set.intersection(b_set)) ` ` ` `else` `:` ` ` `return` `(` `"no common elements"` `)` ` ` ` ` `a ` `=` `[` `1` `, ` `2` `, ` `3` `, ` `4` `, ` `5` `]` `b ` `=` `[` `5` `, ` `6` `, ` `7` `, ` `8` `, ` `9` `]` `print` `(common_member(a, b))` ` ` `a ` `=` `[` `1` `, ` `2` `, ` `3` `, ` `4` `, ` `5` `]` `b ` `=` `[` `6` `, ` `7` `, ` `8` `, ` `9` `]` `print` `(common_member(a, b))` |

**Output:**

{5} No common elements

Last Updated on November 11, 2021 by admin