# 5: Input

**Source**: https://cscircles.cemc.uwaterloo.ca/5-input/
**Parent**: https://cscircles.cemc.uwaterloo.ca/

In the last lesson we discussed user input, but did not really explain how user input is obtained. In Python, the user types one line of input at a time. You should use the `input()` function to actually obtain the next line of input from the user. The `input()` function takes no arguments and always gives back a `str.`

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|  | On this website, all input must be specified before the program runs. If you [run Python interactively at home](https://cscircles.cemc.uwaterloo.ca/run-at-home/) then `input()` actually pauses the program and waits until the user types a line of text.   Also, when working interactively, you can take advantage of the fact that `input()` accepts an optional string input, which will be interpreted as a prompt for the user. E.g., |

```
number = input("Enter a number between 0 and 100. ")
```

Here is an example of using `input()` to get input. The grader will automatically specify the input for the program.

Example

Echoing a line of text

line = input()
print("The first line of input is:", line)

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The next example demonstrates:

- By calling `input()` multiple times, you can access multiple lines of input. The first call to `input()` gets the first line, the second gets the second line, et cetera.
- The string given by `input()` can be converted to an `int` or a `float` (like lesson 4)
- In the second test case, the third line of input is not read, because `input()` is only called twice.

Example

inputString = input()
aFloat = float(inputString)
print(aFloat + 1)
print('Second line:', input())

You may enter input for the program in the box below.

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From now on, most exercises allow the option of entering your own test input. Try the following experiment: press the **Enter input** button above. Leave the input text box empty. Then, press **Run test**. You should get an error like

```
EOFError: EOF when reading a line
```

The acronym **EOF** stands for **E**nd **O**f **F**ile. This message literally means that the program called `input()` but failed to have any available input to read.

- Usually in our lessons, input is provided automatically by the grader, so this error could mean that your program called `input()` too many times, running out and going past the end of the grader's input.
- However, in the example error you just caused, the input was user-provided, and you chose to provide *no* input, so the *first* call to `input()` was already too much.

For the next exercise, you are asked to debug a program which is not working, and make it work. Note that the bug is not a typo, but rather a *logical bug*: the program was not correctly designed to do its job, so you must redesign it a bit.

Coding Exercise: Echo

Write a program that reads one line of input, and prints out that same line two times. For example, if the input is `Echo` the output should be

```
Echo\
Echo
```

Fix the broken sample solution given below. (Or, delete the whole sample solution and start from scratch.)  Hint

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print(input())
print(input())

You may enter input for the program in the box below.

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You can continue to the next lesson, which is about `if` statements.