在 C 中的 getline 中识别 EOF 与换行符

Question

is there any way how to recognize if getline was ended because of newline or because of EOF?

So, I would like to distinguish:

1. alfa \\n beta \\n gama \\n EOF

2. alfa \\n beta \\n gama EOF

In the second case I don't want to read gama as a new string and I want to say, that the reading of last string was not successful. I am using while cycle to read the lines.

I can't edit incoming data.

There is probably possibility to solve this by using getchar. However it makes reading lines more complicated :-/

Thank you so much

Answer 1

Like fgets() , getline() includes the trailing newline in the string. So just check the last character after a successful call to see if it's a '\\n' . If it's something else, you have the last line of a file without a trailing newline.

Answer 2

is there any way how to recognize if getline was ended because of newline or because of EOF?

If the line input stopped due to end-of-file, feof() returns true.

ssize_t nread = getline(&line, &len, stream);
if (feof(stream)) {
  puts("Input ended due to end-of-file");
}
if (nread > 0 && line[nread-1] == '\n') {
  puts("Input ended due to end-of-line");
}

It is possible for both to be false: input error or allocation failure.

---

Concerning fgets() , additional issues occur when the buffer is full or a null character was read.

Answer 3

Thank you for your tips.

Finally I used easier way how to do it.

characters = getline(&line, &len, stream);

if (characters==-1) {puts("Input ended by EOF after \\n");}

if (feof(stdin)) {puts("Input ended by just EOF");}