Extract file extension: Difference between revisions

=={{header|C}}==

<lang C>

#include <assert.h>

#include <ctype.h>

#include <string.h>

#include <stdio.h>

/* Returns a pointer to the extension of 'string'. If no extension is found,

* then returns a pointer to the null-terminator of 'string'. */

char* file_ext(const char *string)

{

assert(string != NULL);

char *ext = strrchr(string, '.');

if (ext == NULL)

return (char*) string + strlen(string);

for (char *iter = ext + 1; *iter != '\0'; iter++) {

if (!isalnum(*iter))

return (char*) string + strlen(string);

}

return ext + 1;

}

int main(void)

{

const char *strings[] = {

"picture.jpg",

"http://mywebsite.con/picture/image.png",

"myuniquefile.longextension",

"IAmAFileWithoutExtension",

"/path/to.my/file",

"file.odd_one"

};

for (int i = 0; i < sizeof(strings) / sizeof(strings[0]); ++i) {

printf("'%s' - '%s'\n", strings[i], file_ext(strings[i]));

}

}

</lang>

{{out}}

<pre>

'picture.jpg' - 'jpg'

'http://mywebsite.con/picture/image.png' - 'png'

'myuniquefile.longextension' - 'longextension'

'IAmAFileWithoutExtension' - ''

'/path/to.my/file' - ''

'file.odd_one' - ''

</pre>