为什么在将char数组复制到结构体时memcpy不工作？ [英] Why doesn't memcpy work when copying a char array into a struct?

问题描述

#define buffer 128    

int main(){
  char buf[buffer]="";

  ifstream infile("/home/kevin/Music/test.mp3",ios::binary);
  infile.seekg(-buffer,ios::end);
  if(!infile || !infile.read(buf,buffer)){
      cout<<"fail!"<<endl;
  }
  ID3v1 id3;
  cout<<sizeof(id3)<<endl;
  memcpy(&id3,buf,128);
  cout<<id3.header<<endl;
}


struct ID3v1{
  char header[3];
  char title[30];
  char artist[30];
  char album[30];
  char year[4];
  char comment[28];
  bool zerobyte;
  bool track;
  bool genre;

};

当我做memcpy时，似乎将太多的数据推入头字段。我需要遍历每个structs成员并复制数据吗？我也使用c ++，但这似乎更多的是一个C的战略。对于c ++有更好的方法吗？

When I do the memcpy, it seems to be pushing too much data into the header field. Do I need to go through each of the structs members and copy the data in? I'm also using c++, but this seems more of a "C" strategy. Is there a better way for c++?

推荐答案

如所有的注释，或当打印C字符串时，操作符<< <期望字符序列被'\0'终止）。

As noted in all the comments (you are missing the '\0' character, or when printing C-Strings the operator<< is expecting the sequence of characters to be '\0' terminated).

尝试：

std::cout << std::string(id3.header, id3.header+3) << std::endl;

这将打印标题字段中的三个字符。

This will print the three characters in the header field.

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