# 11A: Lower Case

**Source**: https://cscircles.cemc.uwaterloo.ca/11a-lower-case/
**Parent**: https://cscircles.cemc.uwaterloo.ca/

*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](https://cscircles.cemc.uwaterloo.ca/6-if/), an [`and` operator](https://cscircles.cemc.uwaterloo.ca/9-else-and-or-not/), and apply some knowledge from [the lesson about strings](https://cscircles.cemc.uwaterloo.ca/7a-strings/).)

Coding Exercise: Lower-case Characters

Define a function `lowerChar(char)` which meets the above description.

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# delete this comment and enter your code here

Enter testing statements like `print(myfunction("test argument"))` below.

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## 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](https://cscircles.cemc.uwaterloo.ca/7c-loops/) 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.

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# first, copy your definition of lowerChar() here
# then define lowerString(string)

Enter testing statements like `print(myfunction("test argument"))` below.

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|  | Later on, you will learn about the `string.lower()` method, which is a built-in way to perform this task. |