急急急！！！！求壹個用c語言對*TXT加密解密的小程序

#define FN "123.txt"

#define FN "456.txt"

#define PASSWORD 12

void jiami(void);

int main(void)

{

int choice;

scanf("%d",&choice);

if(choice==1)

jiami();

else

jiemi();

return 0;

}

void jiami(void)

{

int c;

FILE *fp,*fp1;

fp=fopen(FN,"rb");

fp1=fopen(FN1,"wb");

while(1)

{

c=fgetc(fp);

if(feof(fp))

break;

fputc(c+PASSWARD,fp1);

}

fclose(fp);

fclose(fp1);

}

void jiemi(void)

{

int i;

int c;

FILE *fp,*fp1;

scanf("%d",&i);

if(i!=PASSWARD)

{

printf("密碼錯\n");

return;

}

fp=fopen(FN1,"rb");

fp1=fopen(FN,"wb");

while(1)

{

c=fgetc(fp);

if(feof(fp))

break;

fputc(c-PASSWARD,fp1);

}

fclose(fp);

fclose(fp1);

}