用C语言从二进制文件中读取带结构

Question

我有一些二进制文件，我写结构对象(一个定义的类型)。我希望能读懂特别的(英文)。"结构块"从一个二进制文件转换成一个结构体并显示它。我想到的唯一的想法是创建一个包含所有这些结构的数组，这样我就可以访问普通的结构，但这似乎不是一个有效的方法。如果有人能帮我解决这个问题，我将不胜感激。

Answer 1

我是C的新手，但我想我可以帮上忙。这是你想要做的事情吗?

#include<stdio.h>
#include<stdlib.h>
//just a struct for purposes of demonstration
struct my_struct{
  int prop1;
  int prop2;
};
//writes structs to filename.dat
void writeStruct(int property){
  FILE *file_pointer;
  file_pointer = fopen("filename.dat","ab");
  //define and assign variables to a quick dummy struct
  struct my_struct this_struct;
  this_struct.prop1=property;
  this_struct.prop2=property*2;
  //write struct to file
  fwrite(&this_struct, sizeof(this_struct), 1, file_pointer);
  fclose(file_pointer);
}
//returns the nth struct stored in "filename.dat"
struct my_struct getNthStruct(long int n){
  FILE *file_pointer;
  file_pointer = fopen("filename.dat","rb");
  //will be the struct we retrieve from the file
  struct my_struct nth_struct;
  //set read position of file to nth struct instance in file
  fseek(file_pointer, n*sizeof(struct my_struct), SEEK_SET);
  //copy specified struct instance to the 'nth_struct' variable
  fread(&nth_struct, sizeof(struct my_struct), 1, file_pointer);
  return nth_struct;
}
int main(){
  //write a bunch of structs to a file
  writeStruct(1);
  writeStruct(2);
  writeStruct(3);
  writeStruct(4);
  writeStruct(5);
  //get nth struct (2 is third struct, in this case)
  struct my_struct nth_struct;
  nth_struct=getNthStruct(2);
  printf("nth_struct.prop1=%d, nth_struct.prop2=%dn",
      nth_struct.prop1, //outputs 3
      nth_struct.prop2); //outputs 6
  return 0;
}

为了简洁和隔离核心概念，我故意没有检查明显的错误(文件指针返回NULL，文件长度等)。

欢迎反馈