文件加解密（二）——使用密码

#define _CRT_SECURE_NO_WARNINGS
#define SRC_PATH "C:\\Users\\michael\\Desktop\\yzh.txt"
#define CODE_PATH "C:\\Users\\michael\\Desktop\\yzh_code.txt"
#define DECODE_PATH "C:\\Users\\michael\\Desktop\\yzh_decode.txt"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int getFileSize_C(char * file)
{
int size = -1;
FILE * path;
path = fopen(file, "r");
if (NULL == path)
{
printf("文件打开失败！\n");
return  size; //文件大小不可能为负数
}
else
{
//设置流文件指针的位置,以SEEK_END为起点，偏移量是0,亦即SEEK_END
fseek(path, 0, SEEK_END);
//函数结果：当前文件流指针位置相对于文件起始位置的字节偏移量
size = ftell(path);
fclose(path);
path = NULL;
}

return size;
}

void code_decode_file_with_psw(char* path, char* newpath,char* psw)
{
FILE* pRead = fopen(path, "r");
FILE* pWrite = fopen(newpath, "w");
if (pRead == NULL || pWrite == NULL)
{
return;
}
else
{
int ch = 0;

int fileSize = getFileSize_C(path);
int pswLength = strlen(psw);
for (int i = 0; i < fileSize / pswLength; i++)
{
for (int j = 0; j < pswLength; j++)
{
ch = fgetc(pRead);
fputc(ch^psw[j], pWrite);
}
}
for (int k = 0; k <fileSize % pswLength; k++)
{
ch = fgetc(pRead);
fputc(ch^psw[k], pWrite);
}
}

fclose(pRead);
fclose(pWrite);
pRead = NULL;
pWrite = NULL;

}
void main()
{

code_decode_file_with_psw(SRC_PATH, CODE_PATH,"yzh");
code_decode_file_with_psw(CODE_PATH, DECODE_PATH,"yzh");
system("pause");

}

说明:文本文件使用密码加密时，不能使用r,w方式打开文件。应该使用rb,wb。