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Is it possible to convert a string to a char?
I ask as I am inputting strings from a text file, some of which are numbers so come in as "4" = a string.
atoi will only convert char to int so I need to convert the string to a char in order to get an integer out of it - or is ther a function to convert string to integer?
It depends on what you mean.Quote:
Originally Posted by JayCee++
No, atoi converts a null terminated string to int.Quote:
Originally Posted by JayCee++
You can convert a std::string to an int. There are a few ways, one of which involves a stringstream, e.g.,Quote:
Originally Posted by JayCee++
Code:// str is a std::string
std::istringstream ss(str);
int num;
ss >> num;
laserlight you really are a gem.
That is exactly what I need!
I googled and googled for 'c++ string to integer' but all that ever comes up is 'atoi'.
No.. only the first result is atoi.. the other are excellent forum answers ..many using stringstreams and boost::lexical_cast .Quote:
Originally Posted by JayCee++
Also if you are compiling on a C++11 compatible compiler there are also the stoX series of functions. However for greater compatibility you would probably be better off using the stringstream solution, that works with all standard compliant C++ compilers.
Jim
Know your terminology.
char = a single character
C++ string = std::string
C-style string = array of chars with a '\0' as the last char
A C++ string can be converted to a (constant) C-style string using the c_str() member function.
A string always consists of multiple characters.
Wow.. can't imagine I missed this !Quote:
Originally Posted by jimblumberg
Here's an idea....lets split this thread at this point and everyone interested make a post thereafter adding a lesser known (in your opinion) but handy feature of C++11.
Start a new thread instead.
I tried rg = stoi(ask); where 'rg' is an int and 'ask' is a string but got an error saying 'stoi' was not declared in this scope?Quote:
Originally Posted by jimblumberg
I thought my compiler was C++11 compliant - mingw with Code::Blocks.
How are you telling g++ to use C++0x? Normally you need to pass a parameter to the compiler to compile C++0x (-std=C++0x). Also it may not be available in the version of the compiler you are using, I am not sure what version of g++ added this feature but I believe it was available in version 4.4. This is why I noted that the stringstream method should be preferred since it has always been available in standard C++.
Jim
The compiler is set to 'Have g++ follow the coming C++0x ISO C++ language standard [-std=c++98]' - I thought that meant it was using the latest version.
The command-line should be -std=c++0x, I believe.
c++98 is the older standard, and c++11 (also known as c++0x) is the new one.
So you should find that option.
Yes sorry I looked across a line, it does say c++0x and not 98.
What is the version of your compiler?
Jim
in the help files it says 4.5/6
Show the code where you tried to use the function and post the complete error message exactly as they appear in your development environment.
Jim
This is where I am trying it, 'ask' is being read from a text file and as written it works as it should, if I uncomment the line and comment out the istringstream line instead I get the following error:Code:getline(jcin, ask, '#');
//rg = stoi(ask);
istringstream (ask)>>rg;
cout<<endl<<endl<<"Players rapid play grade : "<<rg;
error : 'stoi' was not declared in this scope
Post your full code.
Then I would say your compiler doesn't support that feature. Stick to the stringstream solution. Or use atoi()
JimCode:rg=atoi(ask.c_str());
Hi Elysia, do you mean the full 550 program or just the function?
Your program. If it's 550 lines long, then make the smallest possible example that demonstrates the error.
That is what I did with the snippet I posted above, it works as it should using 'istringstream' but not if you use 'stoi'
Probably not worth going further with this, I think Jim may well be right that my ompiler doen's have that functionality yet; I will have to look at upgrading but hven't a clue how to go about it! Do you think if I uninstalled Code::Blocks and re-installed the latest cersion that would do it? I am using v10.05. I know that is only the IDE but it installed gcc/mingw along with it when I first installed it.
No. Go explore for mingw in your c::b directory.
When you find it, go download latest mingw and install it into that directory (it would be called mingw or something).
OK, so let me rephrase what I said above:
Show us the smallest possible compilable example that reproduces the issue.
No that "snippet" will not compile as presented. You need to have at least a function main() to have a complete program, along with at least a couple of include files.Quote:
That is what I did with the snippet I posted above, it works as it should using 'istringstream' but not if you use 'stoi'
Jim
Is that "4.5.6" or "4.5 or 4.6"? My copy of g++ 4.6.3 comes with a standard library implementation that does have std::stoi.Quote:
Originally Posted by JayCee++
EDIT:
Wait, there is no 4.5.6, yet.
After retesting with g++ version 4.5.2 and insuring the -std=c++0x was selected stoi() was properly recognized.
Jim
The latest mingw is 4.7 as far as I can make out and I appreciate this is probably not the right place to ask but can anyone tell me where to download an installable copy for windows and how to relace the version I have. I looked on google but only seem to be able to find tar files which I don't know what to do with?
Grab the installer: Download MinGW - Minimalist GNU for Windows from SourceForge.net
(Assuming windows.)
Another MinGW-Like GCC is TDM build of MinGW GCC; version 4.6.1 is the newest on the site.
TDM-GCC
Tim S.