Author Archives: Ismael Lizárraga

Programs in Python are able to receive input coming from the user. The function able to do this is the input function. When this function is called, the program stops and waits for the user to type something. The program continues when the user press return or enter.

Example:

After input(), the Python shell received the text that I wrote and that piece of text was assigned to the variable text, so when I print the text variable I am able to read the same text that I typed.

Also, you can prompt to the user what to input, per example:

If you want to see the input in a new line, use the sequence n at the end of the prompt. Example:

Can you see the difference? In my opinion it looks nicer.

If you expect the user to type a certain type, you can indicate that in your code. Example:

But if I type something different than an integer I get an error message:

So, this is basically how you handle basic input from the user.

#Mastery28

A string is a sequence of characters. You can access the characters one at a time with the bracket operator.

Per example, let’s declare a string variable called car containing a sequence of characters forming the word mazda6.

In this example I’m calling the character corresponding to the third value of index of characters. Remember that the index starts at 0, so the character 0 will be c, the character 1 a, the character 2 z and so on.

Len.

The function len is able to return the numbers of characters contained in a string. Example:

If you want to get the last character of a string you can try something like this:

Traversal.

The process of dealing one string character at time and doing something to it, is called traversal processing.

Example:

This prints individually each of the characters contained inside the car string.

Slices.

Slices are segment of strings. Selecting slices of a certain strings is really easy.

Example:

The slice that I’m calling in this example is one going from the index 0 to the 4^th index. Notice that using the 5 in the brackets means calling the previous character in the index. So the bracket works something like this [firstindex:lastindex+1].

Because…

Immutability.

Strings are immutable, that meaning that you are not able to change an existing string. The best thing you can do to deal with this is creating a new string that is a variation from the original.

Example, let’s call a new model ‘mazda3’:

You can appreciate that I’m calling the slice that contains the word ‘mazda’ and I’m adding a ‘3’ to the end, so I have a new string called new model containing the string ‘Mazda3’

Counting.

Also, you can go a little forward and count the times that a character appears in a string. Let’s count how many times the ‘a’ appears in ‘Mazda6’.

These are somes of the things that you can do with a string. Have fun 😀

#Mastery26