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Sometimes it can be interesting to have a cross-talk between the user and the program, one example being the swirl package that had been designed to teach R in R.

One can ask for user input using the `readline`

command:

```
name <- readline(prompt = "What is your name?")
```

The user can then give any answer, such as a number, a character, vectors, and scanning the result is here to make sure that the user has given a proper answer. For example:

```
result <- readline(prompt = "What is the result of 1+1?")
while(result!=2){
readline(prompt = "Wrong answer. What is the result of 1+1?")
}
```

However, it is to be noted that this code be stuck in a never-ending loop, as user input is saved as a character.

We have to coerce it to a number, using `as.numeric`

:

```
result <- as.numeric(readline(prompt = "What is the result of 1+1?"))
while(result!=2){
readline(prompt = "Wrong answer. What is the result of 1+1?")
}
```

This modified text is an extract of the original Stack Overflow Documentation created by following contributors and released under CC BY-SA 3.0

This website is not affiliated with Stack Overflow

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