直接从std :: istream读入std :: string [英] Reading directly from an std::istream into an std::string

问题描述

有没有反正读取已知数量的字节，直接到std :: string，而不创建一个临时缓冲区这样做？

例如， do it by

  boost :: uint16_t len; 
 is.read（（char *）& len，2）; 
 char * tmpStr = new char [len]; 
 is.read（tmpStr，len）; 
 std :: string str（tmpStr，len）; 
 delete [] tmpStr; 
  

解决方案

std :: string 有一个可以使用的 resize 函数，或者一个同样的构造函数：

  boost :: uint16_t len; 
 is.read（（char *）& len，2）; 
 
 std :: string str（len，'\0'）; 
 is.read（& str [0]，len）; 
  

这是未经测试的，我不知道字符串是否有连续存储。 p>

Is there anyway to read a known number of bytes, directly into an std::string, without creating a temporary buffer to do so?

eg currently I can do it by

boost::uint16_t len;
is.read((char*)&len, 2);
char *tmpStr = new char[len];
is.read(tmpStr, len);
std::string str(tmpStr, len);
delete[] tmpStr;

解决方案

std::string has a resize function you could use, or a constructor that'll do the same:

boost::uint16_t len;
is.read((char*)&len, 2);

std::string str(len, '\0');
is.read(&str[0], len);

This is untested, and I don't know if strings are mandated to have contiguous storage.

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