c++ - 获取线路 : template argument deduction/substitution failed

Question

当我尝试逐行读取命令行的输出时出现此错误:

std::string exec(const char* cmd) {
  FILE* pipe = popen(cmd, "r");
  if (!pipe) return "";

  char buffer[128];
  std::string result = "";

  while (!feof(pipe)) {
    if (fgets(buffer, 128, pipe) != NULL) {
      result += buffer;
    }
  }

  pclose(pipe);

  return result;
}

string commandStr = "echo Hello World";
const char *command = commandStr.c_str();

std::string output = exec(command);

std::string line; 
while (std::getline(output, line)) {
  send(sockfd, line.c_str(), line.length(), 0); 
}

note: template argument deduction/substitution failed: note:
‘std::string {aka std::basic_string}’ is not derived from ‘std::basic_istream<_CharT, _Traits>’ exec(command), line <- Error

Answer 1

要解决错误消息的原因，我猜它来自std::getline() . getline 需要 std::istream作为它的第一个参数。如果你想从 output 中读取，你可以使用 std::stringstream

std::stringstream ss(output);
while (std::getline(ss, line)) {
    /* ... */
}