stdstring

Is std::string size() a O(1) operation? The implementation of STL I'm using is the one built into VC++ Michael Burr If you're asking if MSVC's implementation of string::size() has constant complexity, then the answer is yes. But Don Wakefield mentioned Table 65 in 23.1 of the C++ Standard where it says that the complexity of size() should follow what's said in 'Note A'. Note A says: Those entries marked ‘‘(Note A)’’ should have constant complexity. However, that does not mean that those entries shall have constant complexity. Standards use very specific terminology, and "should" means that it

Is the following C++ code well-formed: void consumer(char const* p) { std::printf("%s", p); } std::string random_string_generator() { // returns a random std::string object } consumer(random_string_generator().c_str()); The problem I have with it is, that after creating the temporary std::string object and taking the c_str() pointer, nothing prevents the std::string object from getting destroyed (or maybe I'm wrong?). Can you please point me to the standard, if the code is OK despite everything. It does work, when I test with g++. The pointer returned by std::string::c_str() points to memory

CString is quite handy, while std::string is more compatible with STL container. I am using hash_map . However, hash_map does not support CString as key, so I want to convert CString into std::string . Writing a CString hash function seems to take a lot of time. CString -----> std::string How can I do this? std::string -----> CString: inline CString toCString(std::string const& str) { return CString(str.c_str()); } Am I right? EDIT: Here are more questions: How can I convert wstring , CString to each other? //wstring -> CString, std::wstring src; CString result(src.c_str()); //CString->wstring

This question already has an answer here: How to concatenate a std::string and an int? 22 answers int i = 4; string text = "Player "; cout << (text + i); I'd like it to print Player 4 . The above is obviously wrong but it shows what I'm trying to do here. Is there an easy way to do this or do I have to start adding new includes? headmyshoulder With C++11, you can write: #include <string> // to use std::string, std::to_string() and "+" operator acting on strings int i = 4; std::string text = "Player "; text += std::to_string(i); Well, if you use cout you can just write the integer directly to

This isn't a design question, really, though it may seem like it. (Well, okay, it's kind of a design question). What I'm wondering is why the C++ std::fstream classes don't take a std::string in their constructor or open methods. Everyone loves code examples so: #include <iostream> #include <fstream> #include <string> int main() { std::string filename = "testfile"; std::ifstream fin; fin.open(filename.c_str()); // Works just fine. fin.close(); //fin.open(filename); // Error: no such method. //fin.close(); } This gets me all the time when working with files. Surely the C++ library would use std

How should I get the number of characters in a string in C++? Eclipse If you're using a std::string , call length() : std::string str = "hello"; std::cout << str << ":" << str.length(); // Outputs "hello:5" If you're using a c-string, call strlen() . const char *str = "hello"; std::cout << str << ":" << strlen(str); // Outputs "hello:5" Or, if you happen to like using Pascal-style strings (or f***** strings as Joel Spolsky likes to call them when they have a trailing NULL), just dereference the first character. const char *str = "\005hello"; std::cout << str + 1 << ":" << *str; // Outputs

I'm looking for the most elegant way to implode a vector of strings into a string. Below is the solution I'm using now: static std::string& implode(const std::vector<std::string>& elems, char delim, std::string& s) { for (std::vector<std::string>::const_iterator ii = elems.begin(); ii != elems.end(); ++ii) { s += (*ii); if ( ii + 1 != elems.end() ) { s += delim; } } return s; } static std::string implode(const std::vector<std::string>& elems, char delim) { std::string s; return implode(elems, delim, s); } Is there any others out there? Andre Holzner Use boost::algorithm::join(..) : #include