How to cross-platform converting char* to long long (64-bit)?

Question

How can I convert a char* string to long long (64-bit) integer?

I use MSVC and GCC compilers and my platforms are Windows, Linux and MAC OS.

Thanks.

Answer 1

Use strtoull for unsigned long long or strtoll for signed long long. On any Unix (Linux, Mac OS X), type man strtoull or man strtoll to get its description. Since both are part of the C99 standard they should be available on any system that supports C. The Linux man pages also have examples on how to use them.

Answer 2

For C++ with a compiler that supports long long int, I would use a std::istringstream object. For instance:

char* number_string;
//...code that initializes number_string

std::istringstream input_stream(number_string);
long long int i64_bit_type;
input_stream >> i64_bit_type;

Answer 3

long long int i;

if(sscanf(string, "%lld", &i) == 1) { ... }

Answer 4

boost::lexical_cast is probably the simplest (in code). See http://www.boost.org/doc/libs/1_47_0/libs/conversion/lexical_cast.htm for more info. Alternately use a stringstream to parse out the numeric value.

Answer 5

 #include <stdlib.h>

 char serial[1000];

 long long var = _atoi64(serial);