如何计算作为输出打印的字符数？
有谁知道我如何打印和计算我打印的字符数？
假设我有一个号码，我通过printf或cout打印。 我怎么能算出我打印出来的实际位数？
根据printf手册页 ，printf返回打印的字符数。
int count = printf("%d", 1000);
如果遇到输出错误，则返回负值。
printf返回它打印的字符数
这是滥用Locale在senes后面进行计数的另一种创造性方法。
这允许您正常使用流，本地将为您记录输出。
这不是生产就绪代码，只是一个概念certificate，以展示如何完成它：
#include #include #include class Counter: public std::codecvt::state_type> { public: Counter(int& count) :m_count(&count) {} private: typedef std::codecvt::state_type> MyType; typedef MyType::state_type state_type; typedef MyType::result result; virtual bool do_always_noconv() const throw() { return false; } virtual result do_out ( state_type& state, const char* fr, const char* fe, const char*& fn, char* to, char* te, char*& tn ) const { // Count the number of characters that will be out on the stream (*m_count) += (fe - fr); // Use the default do_out (which just copies when internal and external are char) return MyType::do_out(state,fr,fe,fn,to,te,tn); } private: int* m_count; }; int main() { // The variable to store the count in int count = 0; // A local object that contains the counting facet. // The counting facet will record output into count. std::locale countingLocale(std::cout.getloc(), new Counter(count)); std::ofstream data; data.imbue(countingLocale); // Impue the stream before opening. data.open("Plop"); data << "Stop" << std::endl; std::cout << "Count: " << count << "\n"; // This should also work with std::cout std::cout.imbue(countingLocale) // Unfortunately there is a bug in the locale code for me that stops this working. }
如果要使用ostream ， pcount()将返回放置的字符数。
使用字符串流预先转换，然后轮询该长度。