#include <stdio.h> #include <stdlib.h> /*   該代碼是對文件讀寫操作的使用 */ #pragma warning(disable:4996) #define MAX_DATA_LEN 4096 //進行加密的函數 int FileSymEnc(char * from, char * to);  void main() {    char * from = "C:/Users/Administrator/Desktop/結構體的拷貝問題.docx";   char * to = "C:/Users/Administrator/Desktop/副本結構體的拷貝問題.docx";   //下面調用函數進行文件的讀寫   int re = FileSymEnc(from, to);   if (re == 0) {     printf("文件讀寫錯誤！");   }   system("pause"); }  int FileSymEnc(char * from, char * to) {   //返回值，以確定執行狀態,-0代表失敗,1代表成功   int re = 1;   //寫了幾個   int writtenLen = 0;   //準備寫幾個   int plainlen = 0;   //在堆區分配4k內存空間   unsigned char * buff = malloc(MAX_DATA_LEN);   buff = memset(buff, 0, MAX_DATA_LEN);   FILE * f = fopen(from, "rb");   FILE * t = fopen(to, "wb");   if (f == NULL) {     printf("打開讀文件錯誤！");     goto END;   }   if (t == NULL) {     printf("打開寫文件錯誤！");     goto END;   }    while (!feof(f))   {      writtenLen = fread(buff, 1, MAX_DATA_LEN, f);     //判讀是否讀到了文件末尾，如果讀到了則跳出循環     if (feof(f))     {       plainlen = writtenLen;       break;     }      if (writtenLen != MAX_DATA_LEN) {       //沒有讀取成功       printf("文件讀入失?。?);       re = 0;       goto END;     }     //讀取成功進行文件的寫入     writtenLen = fwrite(buff, 1, MAX_DATA_LEN, t);     if (writtenLen != MAX_DATA_LEN) {       printf("文件寫入失?。?);       re = 0;       goto END;     }   }    //外面處理不到4K的寫入問題，我們本不用進行格外的小數據讀寫，主不過這和我們的加密方式相關連得   writtenLen = fwrite(buff, 1, plainlen, t);   if (writtenLen != plainlen) {     printf("文件寫入失?。?);     re = 0;     goto END;   }  END:   //堆分配的內存進行釋放   if (buff != NULL) {     free(buff);     buff = NULL;   }   //進行文件的關閉操作    if (f != NULL) {     fclose(f);     f = NULL;   }   if (t != NULL) {     fclose(t);     f = NULL;   }   return re; }