Python dictionary with for loop

In this section, we will learn how to use the for loop with a dictionary. If you have not read about the for loop so far, you can skip this section and get back after learning about the for loop, covered in Chapter 6, Control Statements and Loops. Let's apply the for loop to a dictionary. See the following program named forloopkey.py:

port1 = {21: "FTP", 22 :"SSH", 23: "telnet", 80: "http"} for each in port1: print each

The output is as follows:

Output of program forloopkey.py

The preceding program prints only the keys of the dictionary. If you want to print the key as well as the value, then you can use the items() method. See the following program named forloopitems.py:

port1 = {21: "FTP", 22 :"SSH", 23: "telnet", 80: "http"}
 for k,v in port1.items():
     print k," : ", v

The following screenshot shows the output of the program:

Output of program forloopitems.py

The preceding program seems difficult to understand at first. Let's break the program into two parts...