I'm new to CPP.
I'm trying to create small console app.
my qustion is, is there a way to change char array to integer...?!
for example:
char myArray[]= "12345678" to int = 12345678 ...?!
tnx
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atoi, sscanf, stringstream...deviantfan– deviantfan2014-03-09 08:36:15 +00:00Commented Mar 9, 2014 at 8:36
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@yasouser the question is in C++, not C. Mat's comment is rightphuclv– phuclv2014-03-09 09:57:37 +00:00Commented Mar 9, 2014 at 9:57
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4 Answers
You don't "change" a type. What you want is to create an object of a certain type, using an object of the other type as input.
Since you are new to C++, you should know that using arrays for strings is not recommended. Use a real string:
std::string myString = "12345678";
Then you have two standard ways to convert the string, depending on which version of C++ you are using. For "old" C++, std::istringstream:
std::istringstream converter(myString);
int number = 0;
converter >> number;
if (!converter) {
// an error occurred, for example when the string was something like "abc" and
// could thus not be interpreted as a number
}
In "new" C++ (C++11), you can use std::stoi.
int number = std::stoi(myString);
With error handling:
try {
int number = std::stoi(myString);
} catch (std::exception const &exc) {
// an error occurred, for example when the string was something like "abc" and
// could thus not be interpreted as a number
}
2 Comments
yasouser
Thats a lot to understand for a guy new to C++
Christian Hackl
@yasouser: Yes, but what else should he do? He has to learn about strings anyway if he is currently hacking around with char arrays.
Use boost::lexical_cast:
#include <boost/lexical_cast.hpp>
char myArray[] = "12345678";
auto myInteger = boost::lexical_cast<int>(myArray);
3 Comments
yasouser
For someone new to C++ you should probably point him on how to get Boost.
Griwes
@yasouser, do you consider being new to C++ being the same as being new to thinking, using the internet and computers?
The atoi function does exactly this.
4 Comments
M.M
It has undefined behaviour for some inputs and no failure indication though.
Christian Hackl
@David: atoi cannot distinguish between "0" and "x".
David Schwartz
For a very simple question, it's nice to give a very simple answer. Yes, we can go on about subtle nuances.
Christian Hackl
That's not a nuance. atoi() is a severely broken function, IMO.
Apart from atoi() with C++11 standard compliant compiler you can use std::stoi().
2 Comments
Christian Hackl
atoi() should be avoided because of error handling. std::to_string() does the opposite of what he wants...
yasouser
@ChristianHackl: Thanks for pointing out. I meant to point to stoi.
