找不到任何文件

Question

I'm just starting out with C. In my program the user enters a file name and then I check if the file exists.

Here's the code so far:

    printf("Enter the file name:\n");
    char filename[50];
    fgets(filename, 50, stdin);
    printf("You have entered %s\n", filename);
    if( access(filename, F_OK ) == -1 )
    {
        printf("File not found/access denied.\n");
    }

In the same directory as the program itself I got a file named "steps". However whenever I enter steps or ./steps or even ~/steps I get the file not found error message.

What's the issue here?

By the way I'm on Linux (Ubuntu). Also, I know for certain that I have access to the file - so it's not a matter of permissions.

Answer 1

fgets includes the trailing New-Line in the buffer so access thinks that is part of the file name. You need to strip off the New-Line.

After the fgets, add the following line:

if (filename[strlen(filename)-1] == '\n') filename[strlen(filename)-1] = '\0';

to strip it off.

Edit: As @alk noted (thanks), this should be:

if (strlen(filename) > 0 && filename[strlen(filename)-1] == '\n')
    filename[strlen(filename)-1] = '\0';

&& will not evaluate the right side if the left side evaluates to false so there is no chance of going outside the array bounds.

Answer 2

Because fgets() adds \\n before null character.

For example if you enter "abcd" this would become "abcd\\n"

After reading file name, just replace \\n with null character

 fgets(filename, 50, stdin); 

 if(filename[strlen(filename)-1]=='\n')
    filename[strlen(filename)-1]='\0';