CODEWITHSUNDEEP
cfilefile-io
Bbvarghe
Bbvarghe

Reputation: 265

Wrong File String for fopen?

I have a text filed called fun on my desktop, but when I pass:

FILE* fp;

if((fp = fopen("/Users/<username>/Desktop/fun", "r")) == NULL)
{
    printf("File didn't open\n");
    exit(1);
}

fp is null. I have also tried 

/home/<username>/Desktop/fun

and many variations, and I still can't seem to get the right file path.I am new to using files and C. Any help would be appreciated.

Upvotes: 2

Views: 1059

Answers (7)

Central Scrutinizer
Central Scrutinizer

Reputation: 1

/*===exphome===([o]i)==================================================
 * if SIn is not NULL then
 *    if SIn starts with '~'
 *    then expands $HOME, prepends it to the rest of SIn, and
 *         stores result in SOut or, if SOut==NULL, in a new
 *         allocated string and returns it
 *    else if SOut!=NULL
 *         then copies SIn into SOut and returns SOut
 *         else returns duplicated SIn
 * else returns NULL
=*===================================================================*/
    char *exphome(char *SOut, char *SIn)
    {char *Rt= NULL;
     char *envhome= NULL;

     if(SIn)
        if(*SIn=='~' && (envhome=getenv("HOME")))
          {Rt= malloc(strlen(SIn)+strlen(envhome)+1);
           strcpy(Rt, envhome); strcat(Rt, SIn+1);
           if(SOut) {strcpy(SOut, Rt); free(Rt); Rt= SOut;}
          }
        else if(SOut) {strcpy(SOut, SIn); Rt= SOut;}
        else Rt= strdup(SIn);

     return Rt;
    } /*exphome*/

and then

fopen(exphome(NULL, yourfile), ...)

Upvotes: 0

Rohan
Rohan

Reputation: 53326

fopen() can't expand shell keywords.

Change

FILE* fp = fopen("~/Desktop/fun.txt", "r")

to

FILE* fp = fopen("/home/<yourusername>/Desktop/fun.txt", "r")

Characters like '~', '*' are interpreted by the shell and expanded.

Upvotes: 6

WhoBuntu
WhoBuntu

Reputation: 304

Double-check that you have the correct full file path. Go to the file, right-click on it and select "properties". Are you entering in the path exactly as it is shown, including any suffixes? I.e. if the file is called "file.txt", make sure you include the ".txt" suffix in your code.

Upvotes: -1

JackCColeman
JackCColeman

Reputation: 3807

It looks like the answers have prompted edits of original problem. However, as it is currently written there is NO extension on the file name? Is this really true? or does the file end in "*.txt" etc.?

Upvotes: -1

Barmar
Barmar

Reputation: 780984

You can't use ~ in pathnames to represent the user's home directory. That notation is recognized by shells and some other applications, but it's not part of the Unix filesystem interface. You need to spell out the user's actual home directory.

fopen("/home/username/Desktop/fun.txt", "r")

Upvotes: 4

devnull
devnull

Reputation: 123498

You need to expand ~. Use getenv("HOME").

getenv at opengroup even provides some code:

const char *name = "HOME";
char *value;
value = getenv(name);

Upvotes: 3

Mat
Mat

Reputation: 206689

The ~ in the path is probably the issue. It's your shell that expands that on the command line. fopen doesn't invoke a shell to do substitutions on the path, you'll need to do that yourself.

So pass a complete (relative or absolute) path to fopen, not something that requires shell expansions (~, globbing patterns or shell variables).

Upvotes: 3

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