std::basic_istream::unget - cppreference.com

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# std::basic_istream::unget

From cppreference.com
< cpp‎ | io‎ | basic istream

basic_istream& unget(); |  |

Makes the most recently extracted character available again.

First clears `eofbit`. | (since C++11)

Then the function behaves as `UnformattedInputFunction`. After constructing and checking the sentry object, if any ios_base::iostate flags are set, the function sets `failbit` and returns. Otherwise, calls rdbuf()->sungetc().

If rdbuf()->sungetc() returns Traits::eof(), calls setstate(badbit).

In any case, sets the `gcount()` counter to zero.

### [edit] Parameters

(none)

### [edit] Return value

*this

### [edit] Exceptions

[edit]
failure if an error occurred (the error state flag is not goodbit) and exceptions() is set to throw for that state.

If an internal operation throws an exception, it is caught and badbit is set. If exceptions() is set for `badbit`, the exception is rethrown.

### [edit] Example

Run this code

    #include <sstream>
    #include <iostream>

    int main()
    {
        std::istringstream s1("Hello, world.");
        char c1 = s1.get();
        if (s1.unget())
        {
            char c2 = s1.get();
            std::cout << "Got: " << c1 << " got again: " << c2 << '\n';
        }
    }

Output:

    Got: H got again: H

### [edit] See also

sungetc | moves the next pointer in the input sequence back by one (public member function of `std::basic_streambuf`) [edit]
get | extracts characters (public member function) [edit]
peek | reads the next character without extracting it (public member function) [edit]
putback | puts character into input stream (public member function) [edit]

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