std::basic_istream::ignore - cppreference.com

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# std::basic_istream::ignore

From cppreference.com
< cpp‎ | io‎ | basic istream

basic_istream& ignore( std::streamsize count = 1, int_type delim = Traits::eof() ); |  |

Extracts and discards characters from the input stream until and including `delim`.

`ignore` behaves as an `UnformattedInputFunction`. After constructing and checking the sentry object, it extracts characters from the stream and discards them until any one of the following conditions occurs:

- `count` characters were extracted. This test is disabled in the special case when `count` equals std::numeric_limits<std::streamsize>::max()

- end of file conditions occurs in the input sequence, in which case the function calls setstate(eofbit)

- the next available character `c` in the input sequence is `delim`, as determined by Traits::eq_int_type(Traits::to_int_type(c), delim). The delimiter character is extracted and discarded. This test is disabled if `delim` is Traits::eof()

### [edit] Parameters

count | - | number of characters to extract
delim | - | delimiting character to stop the extraction at. It is also extracted.

### [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

The following example uses `ignore` to skip over non-numeric input:

Run this code

    #include <iostream>
    #include <sstream>
    #include <limits>

    int main()
    {
        std::istringstream input("1\n"
                                 "some non-numeric input\n"
                                 "2\n");
        for(;;) {
            int n;
            input >> n;

            if (input.eof() || input.bad()) {
                break;
            } else if (input.fail()) {
                input.clear(); // unset failbit
                input.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // skip bad input
            } else {
                std::cout << n << '\n';
            }
        }
    }

Output:

    1
    2

### [edit] See also

get | extracts characters (public member function) [edit]
getline | extracts characters until the given character is found (public member function) [edit]

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