String with numbers converted to char (numeric type)

[linxard]

Hello all,

I am new to this board but I am not that new to C++. And I know other programming and scripting languages well.

My problem is to convert a std::string to char (neither char* nor char[]) as a numeric value. Converting to an int or long seems quite easy together with std::stringstream and I got that part working already.

When I try to do the same with char it looks like only the first character in the string is copied to the char variable as an ASCII coded character. Here is a short example, code below:

I want to convert the std::string "42" to a char of numeric value 42. What I get is a char of value 52 which is the ASCII Code for "4" the first character of "42". Other values for the std::string show the same symptom.

char c = 42;
std::string str("42");
std::stringstream sstr;

// before conversion
std::cout << c << std::endl; // outputs "*" (ASCII Code 42)
std::cout << (int) c << std::endl; // outputs "42" (ASCII Code for "*")
std::cout << str << std::endl; // outputs "42"

// string to number conversion - not working as wanted
sstr << str;
sstr >> c;

// after conversion
std::cout << c << std::endl; // outputs "4" (ASCII Code 52)
std::cout << (int) c << std::endl; // outputs 52 (ASCII Code for "4") 

I tried many things to solve this problem. Some led to syntax errors others had no effect at all. The best thing I got was to convert only the first character as seen above.

I have searched Google, the reference and the forums for a solution to this problem but I only found topics about converting different string types to other numeric types (int, long ...) or vice versa.

For me it looks like std::stringstream is handling char as a real single character and not as a numeric value. But I don't know if that is true. If this is the case is there an easy way to have this solved without C style typecasting or a temporarily int?

I am sorry for this long post for this small problem but I wanted to make clear what kind of conversion I need.

Best regards
linxard.

[Disch]

first thing that comes to my mind is to just convert to an int:

char c;
std::stringstream sstr("42");

int temp;
sstr >> temp;  // temp now = 42
c = (char)temp; // cast down to char
cout << c;  // should print "*" 

[linxard]

Hello Disch,

thank you for the fast reply.

Unfortunately your suggestion uses a temporarily variable and C style typecasting. As mentioned in my OP I hope to find a solution that avoids both.

Best regards
linxard.

[Disch]

oh! haw. Sorry. I totally missed that XD. That's what I get for only skimming posts.

I don't have any other ideas for you, sorry.