C++快速读取大文件
debug的时候需要等很长时间读模型,查资料发现了两种快速读取大文件的方法。
test 1:每次读一个字符串
test 2、3一次读取整个文件
{//test 1 string buf; clock_t start = clock(); ifstream fin(objpath); while (fin >> buf); fin.close(); clock_t end = clock(); cout << "time : " << ((double)end - start) / CLOCKS_PER_SEC << "s\n"; } {//test 2 clock_t start = clock(); ifstream fin(objpath, std::ios::binary); vector<char> buf(fin.seekg(0, std::ios::end).tellg()); fin.seekg(0, std::ios::beg).read(&buf[0], static_cast<std::streamsize>(buf.size())); fin.close(); clock_t end = clock(); cout << "time : " << ((double)end - start) / CLOCKS_PER_SEC << "s\n"; } {//test 3 clock_t start = clock(); ifstream fin(objpath); stringstream buf; buf << fin.rdbuf(); fin.close(); clock_t end = clock(); cout << "time : " << ((double)end - start) / CLOCKS_PER_SEC << "s\n"; }
文件大小为112M,花费的时间分别为:
time : 36.809s time : 0.092s time : 4.213s
于是将loader改成了第二种。