stdin getline wrapper

Question

I'd like to read a line from stdin, excluding the newline character. I've written the function:

/* read in a line from stdin, NULL on failure
 * does not include trailing newline
 */
char*
readStdinLine() {
 char* buffer;
 size_t bufsize = 32;
 size_t characters;
 buffer = (char *) malloc(bufsize * sizeof(char));
 if (buffer == NULL)
 return NULL;
 characters = getline(&buffer, &bufsize, stdin);
 buffer[--characters] = '0円';
 char* text = (char *) malloc(characters);
 for (int i = 0; i < characters + 1; i++) {
 text[i] = buffer[i];
 }
 free(buffer);
 return text;
}

This seems inneficient, I'm essentially reading in the line twice, once in getline and once to remove the trailing newline. That doesn't seem like the most memory-efficient algorithm, and I would like to remove the newline without copying, if that is at all possible.

I'm very new to C (have used C++, Java, etc, but never a systems language without objects) so I would appreciate learning all the code style things I've done wrong as well. Thanks!

• Loki Astari: I don't see the need for this. getline() does all this automatically. If you want a version that removed the newline character then you simply remove it (if it exists (Note last line in a file may not have a new line)).
• Aykhan Hagverdili: Do note that getline isn't a standard C function and you should probably tag the question accordingly.

Answer 1

This function can be written like this:

char* readStdinLine()
{
 char* buffer = NULL;
 size_t bufsize = 0;
 ssize_t characters = getline(&buffer, &bufsize, stdin);
 if (characters == -1) {
 free(buffer);
 buffer = NULL;
 }
 else if (buffer[characters-1] == '\n') {
 buffer[characters-1] = '0円';
 }
 return buffer;
}

The getline() function does everything you need. You simply need to check for errors and remove the new line character)