I would like to perform the above mentioned operation, however I would like to make sure that the char array is exactly the same size with the string at hand.
So the real question is, how can I make an array with a size that is going to be determined in the run time?
allocating memory on the free store, and copying the string in one go:
std::string s("abcdef");
...
char* chars=strdup(s.c_str());
You need to free the memory manually, of course. Documentation e.g. on the man page. As @Loki mentions: freeing this memory is done through free(chars), not through delete. Also, you need to include the <cstring> header.
If you want to stay in the c++ world, use a vector; it can be created with two iterators to copy it's data from, and will allocate on the heap, and will cleanup by itself. Isn't that a treat?
std::vector<char> vec( s.begin(), s.end() );
string contains embedded null characters, then your std::vector<> solution will work properly while your strdup solution will not.You can create an array of size known at runtime with the "new" operator:
char* res = new char[str.size()+1];
strncpy(res, str.c_str(), str.size()+1);
string contains any embedded null characters then strncpy will truncate the data. memcpy is more appropriate here, or a proper container such as std::vector<>.std::string s = "hello";
char* c = new char[s.length() + 1]; // '+ 1' is for trailing NULL character.
strcpy(c, s.c_str());
#include <string>
int main(int argc, char *argv[])
{
std::string random_data("This is a string");
char *array=new char[random_data.size()+1];
// do stuff
delete[] array;
return 0;
}
Try:
char* res = new char[str.size()+1](); // Note the () makes sure it is '0' filled.
std::copy(str.begin(), str.end(), res); // Don't need to copy the '\0' as underlying
// array already has '\0' at the end position.
...
delete [] res; // Must not forget to delete.
Or: (preferably)
std::vector<char> res(str.begin(), str.end());
Or: If all you want to do is call a C-unction:
str.c_str()
Use strlen() to find the length of the string, then malloc() a char array of that size.
