一切数据都是字节流

一切文件、数据都是以字节为单位进行读写。

#include <stdio.h>
#include <stdlib.h>

int main() {
  int a = 1234;
  int b = 5;
  unsigned char *tmp = NULL;
  int ret = 0;
  FILE *fd = fopen("C:\\MinGW\\bin\\test.txt","w+");
  printf("size of int is %d\n",sizeof(int));
  if(!fd) {
    printf("open file failed!\n");
  }
  if(!(ret=fwrite(&a,4,1,fd))) {
    printf("failed fwrite,ret is %d\n",ret);
  }
  printf("write ret is %d\n",ret);
  fclose(fd);
  fd = fopen("C:\\MinGW\\bin\\test.txt","r");
  fread(&b,4,1,fd);
  tmp = (unsigned char*)&b;
  printf("now tmp[0] is %d\n",tmp[0]);
  printf("now tmp[1] is %d\n",tmp[1]);
  printf("now tmp[2] is %d\n",tmp[2]);
  printf("now tmp[3] is %d\n",tmp[3]);
  fclose(fd);
  system("pause");
  return 0;
}

其中核心测试数据1234,210,4对应的二进制数据分别如下：

1234 ->10011010010
 210 ->   11010010
   4 ->        100