What is the return value failed FCString::Atof?

Development Programming & Scripting
1

Hello. Atof, Atoi those series of “string to numeric conversion” functions seems to risky.
Even official documents were not mentioned any of that.
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Return value is god’s decision or 0 or what?
If return value is ‘0’ then how distinguish request ‘0’ with error ‘0’?.

2

Well Atof and Atoi returns float and an integer respectively. I’m not quite sure exactly what you’re asking about zero. The purpose of these functions is to convert text to a number, e.g.

FCString::Atoi(TEXT("2.625"))

Will evaluate to an integer value of 2.

UPDATE:

Following the implementation shows that it uses standard C++ wcstof() underneath. So if text cannot be parsed into a float it will return 0.0.

3

The case of next is just fine.
“int number = FCString::Atoi(TEXT(“2.625”))”
but if next return value is zero or what?
“int number = FCString::Atoi(TEXT(“Text…$$%$”))”
What is the invalidated case of “number”?

4

I’ve updated my original answer, so

int number = FCString::Atoi(TEXT("Text...$$%$"))"

number will evaluate to int 0.

5

How to distinguish error from zero?
For Example:

int32 er_number = FCString::Atoi(TEXT(“Some Text”));

and

int32 zero_number = FCString::Atoi(TEXT(“0”));

6

As possible workaround - to write your own input validator before calling atoi

7

Use FCString::IsNumeric to validate before conversion

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