std::string 格式化，如 sprintf

2022-01-12 00:00:00 string formatting c++ stdstring c++-standard-library

我必须用 std::string 格式化="http://en.cppreference.com/w/cpp/io/c/fprintf">sprintf 并将其发送到文件流中.我该怎么做?

I have to format std::string with sprintf and send it into file stream. How can I do this?

推荐答案

你不能直接这样做，因为你没有对底层缓冲区的写访问权(直到 C++11；参见 Dietrich Epp 的 评论).您必须先在 c-string 中执行此操作，然后将其复制到 std::string:

You can't do it directly, because you don't have write access to the underlying buffer (until C++11; see Dietrich Epp's comment). You'll have to do it first in a c-string, then copy it into a std::string:

  char buff[100];
  snprintf(buff, sizeof(buff), "%s", "Hello");
  std::string buffAsStdStr = buff;

但我不确定你为什么不只使用字符串流?我假设您有特定的理由不这样做:

But I'm not sure why you wouldn't just use a string stream? I'm assuming you have specific reasons to not just do this:

  std::ostringstream stringStream;
  stringStream << "Hello";
  std::string copyOfStr = stringStream.str();

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