c - 我需要重命名文件，但我不明白出了什么问题，文件被加密了，但名称没有改变

Question

我需要重命名文件，但是我不明白哪里出了问题，文件被加密了，但是名称没有改变，如何正确使用rename()函数。我需要将文件名更改为“encrypt.yes”

#include <stdio.h>                                                                                  
#include <stdlib.h>  
#include <string.h>


int main(void)                                                                                       
{   

char new[20];                                                                                                
char old[20];
int rename(const char *old, const char *new);                                                                                 
int ch;                                                                                         
FILE *fps;                                                                            
printf("Enter file name (with extension like file.txt) to encrypt : ");
strcpy(new,"encrypt.yes");
rename(old, new);                                
scanf("%s", old);

fps = fopen(old, "r+");                                           
if (fps == NULL) {                                                                              
    printf("Could not open file '%s'\n", old);                                                
    return 1;                                                                                   
}                                                          
while ((ch = fgetc(fps)) != EOF) {                                                              
    ch += 100;                                                                                  
    fseek(fps, -1, SEEK_CUR);                                                                   
    fputc(ch, fps);                                                                             
    fseek(fps, 0, SEEK_CUR);

}                                                 

fclose(fps);                                                                                    

printf("File '%s' encrypted successfully\n", old);                                            
return 0;                                                                                       

}

标签： cwindowsencryption

Answer 1

不知道我是否完全理解您，但我认为您正在尝试按原样修改每个字节。将此答案调整为您的代码，您可以执行以下操作。注意：仍有很大的改进空间和错误处理。

Also, I know you tagged this as Windows, but my Windows VM is screwing up at the moment, so I wrote and tested this code on Linux with gcc. It may work on Windows as-is, but I did not test it. Nonetheless, I think it's straight-forward enough to get you 95% there. The key is opening the file in "r+" mode so you can read from and write to it.

And lastly, don't gloss over the comments you've gotten so far from Paul Ogilvie and David C. Rankin; that's good advice.

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

int main()                                                                                          
{                                                                                                   
    char fname[20];                                                                                 
    int ch;                                                                                         
    FILE *fps;                                                                                      

    printf("Enter file name (with extension like file.txt) to encrypt : ");                         
    scanf("%s", fname);                                                                             

    fps = fopen(fname, "r+");                                                                       
    if (fps == NULL) {                                                                              
        printf("Could not open file '%s'\n", fname);                                                
        return 1;                                                                                   
    }                                                                                               

    while ((ch = fgetc(fps)) != EOF) {                                                              
        ch += 100;                                                                                  
        fseek(fps, -1, SEEK_CUR);                                                                   
        fputc(ch, fps);                                                                             
        fseek(fps, 0, SEEK_CUR);                                                                    
    }                                                                                               

    fclose(fps);                                                                                    

    printf("File '%s' encrypted successfully\n", fname);                                            
    return 0;                                                                                       
}