std::lexical_cast - is there such a thing?
Only partially.
C++11 <string>
has std::to_string
for the built-in types:
[n3290: 21.5/7]:
string to_string(int val); string to_string(unsigned val); string to_string(long val); string to_string(unsigned long val); string to_string(long long val); string to_string(unsigned long long val); string to_string(float val); string to_string(double val); string to_string(long double val);
Returns: Each function returns a
string
object holding the character representation of the value of its argument that would be generated by callingsprintf(buf, fmt, val)
with a format specifier of"%d"
,"%u"
,"%ld"
,"%lu"
,"%lld"
,"%llu"
,"%f"
,"%f"
, or"%Lf"
, respectively, wherebuf
designates an internal character buffer of sufficient size.
There are also the following that go the other way around:
[n3290: 21.5/1, 21.5/4]:
int stoi(const string& str, size_t *idx = 0, int base = 10); long stol(const string& str, size_t *idx = 0, int base = 10); unsigned long stoul(const string& str, size_t *idx = 0, int base = 10); long long stoll(const string& str, size_t *idx = 0, int base = 10); unsigned long long stoull(const string& str, size_t *idx = 0, int base = 10); float stof(const string& str, size_t *idx = 0); double stod(const string& str, size_t *idx = 0); long double stold(const string& str, size_t *idx = 0);
However, there's nothing generic that you can use (at least not until TR2, maybe!), and nothing at all in C++03.
No it isn't, even in C++11, but it's proposed for inclusion in Technical Report 2, the next set of std library extensions.
There's no std::lexical_cast, but you can always do something similar with stringstreams:
template <typename T>
T lexical_cast(const std::string& str)
{
T var;
std::istringstream iss;
iss.str(str);
iss >> var;
// deal with any error bits that may have been set on the stream
return var;
}