CODEWITHSUNDEEP
inputiolua
Raghap
Raghap

Reputation: 163

io.read is skipped Lua

I tried to make a calculator as a good first assignment. Though I'm having an issue the io.read function.

Here's my code

io.write("let's try making a calculator in LUA!\n\n")

io.write("First number?\n> ")
firstNum = io.read("*n")

io.write("Second number?\n> ")
secNum = io.read("*n")

io.write("Operator?\n>")
op = io.read()

--rest of code goes here--

It lets me input firstNum and secNum, but once it reaches the op one it just quits with no error. Here's the output

➜ lua test.lua 
let's try making a calculator in LUA!!

First number?
> 10
Second number?
> 20
Operator?
>⏎

Any idea what I'm doing wrong here?

Upvotes: 4

Views: 1543

Answers (1)

Yu Hao
Yu Hao

Reputation: 122383

The cause is, a number is read until you press the ENTER key. The newline character is still in the input buffer, and is then read by the following io.read().

One option is to read op until it's valid. For example, to skip whitespace characters:

repeat op = io.read() until op:match "%S"

or, to read only one punctuation character:

repeat op = io.read() until op:match "%p"

Upvotes: 3

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