std

I've been pouring over the format description and source code for the 7z archive format, but I'm still having trouble writing a valid container. I assume I can create an empty container... anyway here's my start: std::ofstream ofs(archivename.c_str(), std::ios::binary|std::ios::trunc); Byte signature[6] = {'7', 'z', 0xBC, 0xAF, 0x27, 0x1C}; Byte major = 0; Byte minor = 3; ofs.write((const char*)signature, 6); ofs.write((const char*)major, 1); ofs.write((const char*)minor, 1); UInt64 offset = 0; UInt64 size = 0; UInt32 crc = 0; ofs.write((const char*)offset, 4); ofs.write((const char*)size, 8);

Is there any native (cross platform) C++ function in any of standard libraries which returns the actual length of std::string ? Update: as we know std::string.length() returns the number of bytes not the number of characters. I already have a custom function which returns the actual one, but I'm looking for an standard one. codecvt ought to be helpful, the Standard provides implementations for UTF-8, for example codecvt_utf8<char32_t>() would be appropriate in this case. Probably something like: wstring_convert< codecvt_utf8<char32_t>, char32_t >().from_bytes(the_std_string).size() Actual

Here is a simple test program that illustrates the problem I faced: #include <iostream> #include <stdlib.h> #include <inttypes.h> #include <vector> using namespace std; typedef unsigned char Byte; int main( ) { uint32_t ui32 = 12; size_t sizeofUi32 = sizeof ui32; cout << "sizeofUi32: " << sizeofUi32 << endl; vector<Byte> v(10); std::copy(&ui32, &ui32 + sizeof ui32, &v[4]); uint32_t result = 0; std::copy(&v[4], &v[4] + sizeof ui32, &result); cout << "Result: " << result << " sizeofUi32: " << sizeofUi32 << endl; return 0; } output: sizeofUi32: 4 Result: 12 sizeofUi32: 17179869184 I thought this

I want to track all the memory(size allocated by std lib) allocated by all STL containers like map,list,vector etc. I just want to track STL container not regular object creation. Basically want to override new and delete of std lib. Example class demo { public: int i; std::list<int> mylist; } int main() { demo dd = new demo(); // -> Don't want to track this. Just want to track // mylist(size of my list) } I found out that std has it's own allocator option. For example list has it is allocator template < class T, class Alloc = allocator<T> > class list; What is the default allocator if I don't

The output of the following code: #include <limits> #include <iostream> #include <iomanip> #include <limits> #include <string> #include <sstream> using namespace std; inline string lexical_cast(const float arg) { stringstream ss; ss << fixed << setprecision(numeric_limits<float>::digits10) << arg; if (!ss) throw "Conversion failed"; return ss.str(); } int main() { cout << numeric_limits<float>::digits10 << '\n'; cout << lexical_cast(32.123456789) << '\n'; } is: 6 32.123455 I expected, and wanted: 6 32.1234 because, to the best of my knowledge, that's the extent of what a float can reliably

I would like to know if there is an efficient way to remove objects from a container based on values of member fields of the objects. For example, I can do the following using stl::unique with a list of strings: #include<iostream> #include<list> #include<string> #include<algorithm> using namespace std; bool stringCompare(const string & l, const string & r) { return (l==r); } int main() { list<string> myStrings; myStrings.push_back("1001"); myStrings.push_back("1001"); myStrings.push_back("81"); myStrings.push_back("1001"); myStrings.push_back("81"); myStrings.sort(); myStrings.erase(unique

Consider this code: #include <iostream> template<class C> struct time { }; int main() { } It produces (GCC 4.5): error: ‘template<class C> struct time’ redeclared as different kind of symbol /usr/include/time.h:186:15: error: previous declaration of ‘time_t time(time_t*)’ Why does iostream include time_t time(time_t*) ? Why does iostream include time_t time(time_t*) outside std namespace? (unanswered) Why, if I remove template<class C> , do I not get this error? If you run g++ -H -Wall -c testim.cc (where testim.cc is your example) you'll see that .... /usr/include/c++/4.6/bits/ios_base.h ....