getting file extention from filename? split?

[EricM]

I have written perl and VB and this is my very first attept at C

there is a variable called name
which is a filename like somefile.ext

i want to check that name does not have the extention .mp3 or .rar or .ace (make it easy for me to add new types)
and if it is one of those extensions then it should do this

addreply(553, MSG_BAD_FILE_TYPE, name);
goto end;

a way to get whatever letters are after the last dot into a string would be useful

[Technocrat]

What type is the VAR you are holding the string in?

[EricM]

im not sure
its a part of this function is that what you mean?

void dostor(char *name, const int append, const int autorename)

its name that contains the filename

[Technocrat]

Well I am not going to write the whole thing for you but you can use some code I have used before to get the right part of a string. Just send it your sting and 4 for the length, then you can look the returned value and see if it has the extentions you are looking for

/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
//| Function:    *right()
//| In:            const char *chString
//|                    In Char Or String Of Chars
//|                unsigned int len
//|                    Length To Trim
//| Return:        char*
//| Notes:        This Function Trims Chars From Right To Left  <---
//| Example:    char p[] = "TTTT1234";
//|                LPCTSTR t;
//|                t = right(p,3);        //Should Return "234"
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/

char *right(const char *chString,unsigned int len)
{
/*>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>*/
    unsigned int i;                //Loop VAR
    int k, nIndex;                //More Loop VARs
    char *buf;                    //Temp String VAR
/*<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<*/

    if (!strlen(chString))                        //If There Is No String
        return NULL;                            //Return NULL

    if (len > strlen(chString))                    //If The Amount To Copy Is Larger Than The String
        len = strlen(chString);                    //Set The Length To The Length Of The String

    buf = (char *)malloc(len + 1);

    //Copy The Part We Want From The Orginal String To The Result
    for (i = 0, nIndex = ((strlen(chString))-len), k = 0; i < len; i++)    
    {        
        if (chString[i] != '\0')            //If Not A NULL Char        
            buf[k++] = chString[nIndex++];
        else
            break;
    }

    buf[k] = '\0';                        //Add A NULL Char To The End Of The String

    return buf;

} 

[parksie]

What if your extension is more or less than 3 characters?

If you're on Windows:

splitpath, _wsplitpathSee Also
File Handling Routines | _fullpath | _getmbcp | _makepath | _setmbcp
Requirements
Routine Required header Compatibility
_splitpath <stdlib.h> Win 98, Win Me, Win NT, Win 2000, Win XP
_wsplitpath <stdlib.h> or <wchar.h> Win 98, Win Me, Win NT, Win 2000, Win XP

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.
Break a path name into components.

void _splitpath(
const char *path,
char *drive,
char *dir,
char *fname,
char *ext
);
void _wsplitpath(
const wchar_t *path,
wchar_t *drive,
wchar_t *dir,
wchar_t *fname,
wchar_t *ext
);
Parameters
path
Full path
drive
Optional drive letter, followed by a colon (
dir
Optional directory path, including trailing slash. Forward slashes ( / ), backslashes ( \ ), or both may be used.
fname
Base filename (no extension)
ext
Optional filename extension, including leading period (.)
Remarks
The _splitpath function breaks a path into its four components. _splitpath automatically handles multibyte-character string arguments as appropriate, recognizing multibyte-character sequences according to the multibyte code page currently in use. _wsplitpath is a wide-character version of _splitpath; the arguments to _wsplitpath are wide-character strings. These functions behave identically otherwise.

Generic-Text Routine Mappings

TCHAR.H routine _UNICODE & _MBCS not defined _MBCS defined _UNICODE defined
_tsplitpath _splitpath _splitpath _wsplitpath

Each argument is stored in a buffer; the manifest constants _MAX_DRIVE, _MAX_DIR, _MAX_FNAME, and _MAX_EXT (defined in STDLIB.H) specify the maximum size necessary for each buffer. The other arguments point to buffers used to store the path elements. After a call to _splitpath is executed, these arguments contain empty strings for components not found in path. You can pass a NULL pointer to _splitpath for any component you don't need.

Requirements
Routine Required header Compatibility
_splitpath <stdlib.h> Win 98, Win Me, Win NT, Win 2000, Win XP
_wsplitpath <stdlib.h> or <wchar.h> Win 98, Win Me, Win NT, Win 2000, Win XP

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.

Example
/* MAKEPATH.C */

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

void main( void )
{
char path_buffer[_MAX_PATH];
char drive[_MAX_DRIVE];
char dir[_MAX_DIR];
char fname[_MAX_FNAME];
char ext[_MAX_EXT];

_makepath( path_buffer, "c", "\\sample\\crt\\", "makepath", "c" );
printf( "Path created with _makepath: %s\n\n", path_buffer );
_splitpath( path_buffer, drive, dir, fname, ext );
printf( "Path extracted with _splitpath:\n" );
printf( " Drive: %s\n", drive );
printf( " Dir: %s\n", dir );
printf( " Filename: %s\n", fname );
printf( " Ext: %s\n", ext );
}

Output
Path created with _makepath: c:\sample\crt\makepath.c

Path extracted with _splitpath:
Drive: c:
Dir: \sample\crt\
Filename: makepath
Ext: .c

See Also
File Handling Routines | _fullpath | _getmbcp | _makepath | _setmbcp

Not tried that, so not sure how long _MAX_EXT is...

[EricM]

its running on linux
the above doesnt work i get errors:

ftpd.c: In function `dostor':
ftpd.c:3327: parse error before `char'
ftpd.c:3335: `chString' undeclared (first use in this function)
ftpd.c:3335: (Each undeclared identifier is reported only once
ftpd.c:3335: for each function it appears in.)
ftpd.c:3336: warning: `return' with a value, in function returning void
ftpd.c:3338: `len' undeclared (first use in this function)
ftpd.c:3344: `i' undeclared (first use in this function)
ftpd.c:3344: `nIndex' undeclared (first use in this function)
ftpd.c:3344: `k' undeclared (first use in this function)
ftpd.c:3346: empty character constant
ftpd.c:3352: empty character constant
ftpd.c:3354: warning: `return' with a value, in function returning void
ftpd.c:3253: label `end' used but not defined
ftpd.c: At top level:
ftpd.c:3360: parse error before `if'
ftpd.c:3377: parse error before `553'
they go on...


btw does anyone know why this wont work?
upload.pl is a shell script and will output either 1 or 0

if (system("/root/upload.pl") != 1) {
addreply(553, MSG_SANITY_FILE_FAILURE, name);
goto end;
}

[Technocrat]

What I gave you was another function and it looks like you are trying to put it inside of ANOTHER function. You cant do that.

Since you are just now telling us you are using Linux, Parksie's example will not work (I dont think).

I think you need to spend sometime learning more basic stuff....to be blunt because you really do seem to know what you are doing. Saying that, unless someone is really nice, they are not going to write this for you.

[MoMad]

char* getExt( const char* filename, char* extbuffer )
{
    // the dot
    const char dot = '.'; 

    // counter, position
    int n = -1, pos = 0;

    // empty extension buffer
    extbuffer[0] = NULL;

    // Get the position of last dot
    while (filename[++n])
    {
        if (filename[n] == dot)
        {
            // last position will overide this
            pos = n;
        }
    }

    // if no dot found, return null (.txt is invalid)
    if (!pos)
    {
        return extbuffer;
    }

    // the length of the string
    int len = n;

    // terminate the extension string with null
    extbuffer[len - ++pos] = NULL;

    // Now get everything from the dot to the end
    while (filename[--n] != dot)
    {
        extbuffer[len - ++pos] = filename[n];
    }

    // Return the extention
    return extbuffer;
} 

[MoMad]

use it like:

if (!strncmp(getExt(filename, buff), "htm", 3)) {
 // htm or html
}
else
{
  // bla
}