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std::basic_istream::peek

From cppreference.com
< cpp‎ | io‎ | basic istream
 
 
Input/output library
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(deprecated in C++98)
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(C++11)
 
 
int_type peek();

Behaves as UnformattedInputFunction. After constructing and testing the sentry object, reads the next character from the input stream without extracting it.

Contents

[edit] Parameters

(none)

[edit] Return value

If good() == true, returns the next character as obtained by rdbuf()->sgetc()

Otherwise, returns Traits::eof().

[edit] Exceptions

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

#include <sstream>
#include <iostream>
int main()
{
    std::istringstream s1("Hello, world.");
    char c1 = s1.peek();
    char c2 = s1.get();
    std::cout << "Peeked: " << c1 << " got: " << c2 << '\n';
}

Output:

Peeked: H got: H

[edit] See also

reads one character from the input sequence without advancing the sequence
(public member function of std::basic_streambuf) [edit]
extracts characters
(public member function) [edit]
unextracts a character
(public member function) [edit]