# 11A: Lower Case

Lesson 11 has three parts A, B, C which can be completed in any order.

This lesson contains an exercise where you need to write two functions: one will use the other to accomplish its goal. The goal is to eventually write a function `lowerString` that can convert all of the letters in a string to lower case. (A, B, C are upper case letters and a, b, c are lower case.) For example, the result of

`lowerString("This string has 9 CAPITAL letters (& Punctuation)!")`
should be

`"this string has 9 capital letters (& punctuation)!"`

## Step 1: Characters

The first step is to write a function `lowerChar(char)` that can return the result of converting a single character `char` to lower case. It should do the following:

• if the input character `char` is a capital letter (between '`A`' and '`Z`'), it should return the lower-case version of the letter (between '`a`' and '`z`')
• in all other cases, it should return the same `char` which was input.

(In order to do the first step, you will have to use an `if` statement, an `and` operator, and apply some knowledge from the lesson about strings.) Coding Exercise: Lower-case Characters
Define a function `lowerChar(char)` which meets the above description.
Enter testing statements like `print(myfunction("test argument"))` below.

## Step 2: Strings

Now, you will write a second function `lowerString(string)` which will return the result of converting the entire string to lower case, by calling `lowerChar` on each character. We suggest you do this as follows:

• first, copy the definition of `lowerChar(char)` from your solution to the first part
• then define a second function, `lowerString(string)`
• on the first line inside lowerString, initialize a variable `result = ""` equal to the empty string
• use a for loop with `i` and set `result = result + lowerChar(string[i])`
• finally, `return result` Coding Exercise: Lower-case Strings
Define a function `lowerString(string)` which returns the result of converting `string` to lower case.
Enter testing statements like `print(myfunction("test argument"))` below. Later on, you will learn about the `string.lower()` method, which is a built-in way to perform this task.