CODEWITHSUNDEEP
c++stream
John Kalane
John Kalane

Reputation: 1185

Why does istream::get set cin.fail when '\n' is the first character?

Why these two functions istream::get(char*, streamsize) and istream::get(char*, streamsize, char) set the cin.fail bit when they find '\n' as the first character in the cin buffer?

As can be seen here, that's the behavior of the two overloads mentioned above. I'd like to know what was the purpose in designing these functions this way ? Note that both functions leave the character '\n' in the buffer, but if you call any of them a second time, they will fail because of the newline character, as shown in the link. Wouldn't it make more sense to make these two functions not to leave the character '\n' in the buffer, as the overloads of the function istream::get() and istream::getline() do ?

Upvotes: 0

Views: 272

Answers (1)

Olaf Dietsche
Olaf Dietsche

Reputation: 74118

With std::istream::getline, if the delimiting character is found it is extracted and discarded. With std::istream::get the delimiting character remains in the stream.

With getline you don't know, if the delimiting character was read and discarded or if just n - 1 characters where read. If you only want to read whole lines, you can use get and then peek for the next character and see if it is a newline or the given delimiter.

But if you want to read whole lines up to some delimiter, you might also use std::getline, which reads the complete line in any case.

Upvotes: 1

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