string type casting to int

[Eli Luong]

I had a string element, using the string class, and I'm trying to
convert this to an integer. I took a substring of the string because
that is where the integer is located, and I tried to use atoi() on it,
but it seems atoi() accepts char* type variable, whereas what I have is
a string. I've tried searching for a method to convert a string to an
integer, but haven't found a clear answer and was hoping someone here
can help.

Thanks,
- Eli

 

[Victor Bazarov]

I had a string element, using the string class, and I'm trying to
convert this to an integer. I took a substring of the string because
that is where the integer is located, and I tried to use atoi() on it,
but it seems atoi() accepts char* type variable, whereas what I have
is a string. I've tried searching for a method to convert a string to
an integer, but haven't found a clear answer and was hoping someone
here can help.

Use 'strtol' instead of 'atoi' and read up on 'c_str' member of the
std::string class.

V

 

[atomik.fungus]

Eli Luong ha escrito:

I had a string element, using the string class, and I'm trying to
convert this to an integer. I took a substring of the string because
that is where the integer is located, and I tried to use atoi() on it,
but it seems atoi() accepts char* type variable, whereas what I have is
a string. I've tried searching for a method to convert a string to an
integer, but haven't found a clear answer and was hoping someone here
can help.

Thanks,
- Eli

I had to do something similar once
You can try to make a new function which creates a an array of char's
big enough to fit in anything you want and read the string element by
element copying it in your array. Once it is done you can use atoi.
First you must find the length of the string.

Note that im a newbie and there is probably an easier and more
effective way

 

[atomik.fungus]

The answer came before i finished my reply

 

[Marcus Kwok]

Use 'strtol' instead of 'atoi' and read up on 'c_str' member of the
std::string class.

There is also the method using stringstreams given in the FAQ.

 

[Eli Luong]

There is also the method using stringstreams given in the FAQ.

Thanks, I'll take a look at both of considerations.

 

[Lars Tetzlaff]

I had a string element, using the string class, and I'm trying to
convert this to an integer. I took a substring of the string because
that is where the integer is located, and I tried to use atoi() on it,
but it seems atoi() accepts char* type variable, whereas what I have is
a string. I've tried searching for a method to convert a string to an
integer, but haven't found a clear answer and was hoping someone here
can help.

Thanks,
- Eli

You may try boost::lexical_cast like:

int aVal = boost::lexical_cast<int>( "1234" );

http://www.boost.org/libs/conversion/lexical_cast.htm#examples