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。