# How to ask for numerica input

**URL:** <https://www.ruby-forum.com/t/how-to-ask-for-numerica-input/176136>\
**Category:** Ruby\
**Created:** [September 25, 2009, 3:53am UTC](https://www.ruby-forum.com/t/how-to-ask-for-numerica-input/176136 "2009-09-25T03:53:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![fim32](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/779978/32.png) [@fim32](https://www.ruby-forum.com/u/fim32)\
**Post date:** [September 25, 2009, 3:53am UTC](https://www.ruby-forum.com/t/how-to-ask-for-numerica-input/176136/1 "2009-09-25T03:53:34Z")

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I am trying to make a simple temperature converter, and I want to ask  
for F temperature (numerical value)

what command do I use?

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**Author:** ![fim32](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/779978/32.png) [@fim32](https://www.ruby-forum.com/u/fim32)\
**Post date:** [September 25, 2009, 4:13am UTC](https://www.ruby-forum.com/t/how-to-ask-for-numerica-input/176136/2 "2009-09-25T04:13:01Z")

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Hi –

On Fri, 25 Sep 2009, Fred I. wrote:

> I am trying to make a simple temperature converter, and I want to ask  
> for F temperature (numerical value)
> 
> what command do I use?

The bread-and-butter way to get keyboard input is with gets:

print "Enter a number: "  
line = gets

and then, since line is a string:

num = line.to\_i

You can get fancier with error-checking, etc., but that’s the basic  
idea.

David

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<div class="post-metadata">

**Author:** ![fim32](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/779978/32.png) [@fim32](https://www.ruby-forum.com/u/fim32)\
**Post date:** [September 25, 2009, 2:10pm UTC](https://www.ruby-forum.com/t/how-to-ask-for-numerica-input/176136/3 "2009-09-25T14:10:07Z")

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Hi,

Am Freitag, 25. Sep 2009, 11:12:37 +0900 schrieb David A. Black:

> You can get fancier with error-checking, etc., but that’s the basic  
> idea.

This does the error checking:

num = Integer line

Bertram