文本和二进制的加密及获取二进制文件的大小

1.EOF

在C语言中，或更精确地说成C标准函数库中表示文件结束符（end of file）。在这种以EOF作为文件结束标志的文件，必须是文本文件。在文本文件中，数据都是以字符的ASCII代码值的形式存放。我们知道，ASCII代码值的范围是0~127，不可能出现-1，因此可以用EOF作为文件结束标志。

2.函数feof　　

函数原型： int feof(FILE *fp)

功能：判断文件是否结束

返回值：文件结束，返回真(非0)，文件未结束，返回0

3.实例

• 非密码加密  txt

  #define  _CRT_SECURE_NO_WARNINGS
  #include <stdio.h>
  #include <stdlib.h>
  
  void jia(char *path,char *newpath)
  {
      FILE *pfr = fopen(path, "r");
      FILE *pfw = fopen(newpath, "w");
  
      char ch = 0;
      while (ch != EOF) //EOF 文件结束
      {
          ch = fgetc(pfr);//读取，EOF
          if (ch != EOF)
          {
              ch += 1;
              fputc(ch, pfw);
          }
  
      }
      fclose(pfr);
      fclose(pfw);
  
  }
  
  void jie(char *path, char* newpath)
  {
      FILE *pfr = fopen(path, "r");
      FILE *pfw = fopen(newpath, "w");
  
      char ch = 0;
      while (ch != EOF) //EOF 文件结束
      {
          ch = fgetc(pfr);//读取，EOF
          if (ch != EOF)
          {
              ch -= 1;
              fputc(ch, pfw);
          }
  
      }
  
      fclose(pfr);
      fclose(pfw);
  
  }
  
  void main()
  {
      char *path = "C:\\Users\\sjx\\Desktop\\test\\Q.txt";
      char *pathjia = "C:\\Users\\sjx\\Desktop\\test\\Qjia.txt";
      char *pathjie = "C:\\Users\\sjx\\Desktop\\test\\Qjie.txt";
      jia(path, pathjia);
      jie(pathjia, pathjie);//路径
  
      system("pause");
  }
  
      system("pause");
  
  }

• 根据密码加密  (二进制文件加密解密)

  #define _CRT_SECURE_NO_WARNINGS
  #include <stdio.h>
  #include <stdlib.h>
  
  char *path = "C:\\Users\\sjx\\Desktop\\test\\Q.exe";
  char *pathjia = "C:\\Users\\sjx\\Desktop\\test\\Qjia.exe";
  char *pathjie = "C:\\Users\\sjx\\Desktop\\test\\Qjie.exe";
  
  void run(char *path, char *newpath)
  {
      FILE *pfr = fopen(path, "rb");
      FILE *pfw = fopen(newpath, "wb");
      if (pfr==NULL || pfw ==NULL)
      {
          return;
      }
      else
      {
          char  ch;
              while (!feof(pfr))
              {
              char ch = fgetc(pfr);
              char newch = ch ^ 3;
              fputc(newch, pfw);
              }
          fclose(pfr);
          fclose(pfw);
      }
  
  }
  
  void main()
  {
  
      run(path, pathjia);
      run(pathjia, pathjie);
      /*printf("%d", getfilesizeseek(path));*/
  
      system("pause");
  }

3.获取二进制文件的大小

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

char *path = "C:\\Users\\sjx\\Desktop\\test\\Q.exe";
char *pathjia = "C:\\Users\\sjx\\Desktop\\test\\Qjia.exe";
char *pathjie = "C:\\Users\\sjx\\Desktop\\test\\Qjie.exe";

int getfilesize(char *path)
{
    int i = -1;
    FILE *pfr = fopen(path, "rb");
    if (pfr == NULL )
    {
        return -1;
    }
    else
    {
        while (!feof(pfr))
        {
            char ch=fgetc(pfr);

            i++;//读取一个字符，前进一次
        }

        fclose(pfr);
        return i;
    }
}

int getfilesizeseek(char *path)
{

    FILE *pfr = fopen(path, "rb");
    if (pfr == NULL)
    {
        return -1;
    }
    else
    {
        fseek(pfr, 0, SEEK_END);//文件指针移动末尾
        int length = ftell(pfr);//获取当前文件指针距离开头的长度

        fclose(pfr);
        return length;

    }
}

int main()
{

    run(path, pathjia);
    run(pathjia, pathjie);
    /*printf("%d", getfilesizeseek(path));*/

    system("pause");
}