C++
| Compiler support |
| Freestanding and hosted |
| Language |
| Standard library |
| Standard library headers |
| Named requirements |
| Feature test macros (C++20) |
| Language support library |
| Concepts library (C++20) |
| Diagnostics library |
| Memory management library |
| Metaprogramming library (C++11) |
| General utilities library |
| Containers library |
| Iterators library |
| Ranges library (C++20) |
| Algorithms library |
| Strings library |
| Text processing library |
| Numerics library |
| Date and time library |
| Input/output library |
| Filesystem library (C++17) |
| Concurrency support library (C++11) |
| Execution control library (C++26) |
| Technical specifications |
| Symbols index |
| External libraries |
[edit] Strings library
| Classes |
| basic_string |
| basic_string_view(C++17) |
| char_traits |
[edit] std::basic_string
| Member functions | | basic_string::basic_string | | basic_string::~basic_string | | basic_string::operator= | | basic_string::assign | | basic_string::assign_range(C++23) | | basic_string::get_allocator | | Element access | | basic_string::at | | basic_string::operator[] | | basic_string::front(DR*) | | basic_string::back(DR*) | | basic_string::data | | basic_string::c_str | | basic_string::operator basic_string_view(C++17) | | Iterators | | basic_string::beginbasic_string::cbegin(C++11) | | basic_string::endbasic_string::cend(C++11) | | basic_string::rbeginbasic_string::crbegin(C++11) | | basic_string::rendbasic_string::crend(C++11) | | Search | | basic_string::find | | basic_string::rfind | | basic_string::find_first_of | | basic_string::find_first_not_of | | basic_string::find_last_of | | basic_string::find_last_not_of | | | Modifiers | | basic_string::clear | | basic_string::insert | | basic_string::insert_range(C++23) | | basic_string::erase | | basic_string::push_back | | basic_string::pop_back(DR*) | | basic_string::append | | basic_string::append_range(C++23) | | basic_string::operator+= | | basic_string::replace | | basic_string::replace_with_range(C++23) | | basic_string::copy | | basic_string::resize | | basic_string::resize_and_overwrite(C++23) | | basic_string::swap | | Capacity | | basic_string::empty | | basic_string::sizebasic_string::length | | basic_string::max_size | | basic_string::reserve | | basic_string::capacity | | basic_string::shrink_to_fit(DR*) | | Operations | | basic_string::compare | | basic_string::starts_with(C++20) | | basic_string::ends_with(C++20) | | basic_string::contains(C++23) | | basic_string::substr | | | Constants | | basic_string::npos | | Non-member functions | | operator+ | | swap(std::basic_string) | | erase(std::basic_string)erase_if(std::basic_string)(C++20)(C++20) | | I/O | | operator<<operator>> | | getline | | Comparison | | operator==operator!=operator<operator>operator<=operator>=operator<=>(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) | | Numeric conversions | | stoistolstoll(C++11)(C++11)(C++11) | | stoulstoull(C++11)(C++11) | | | stofstodstold(C++11)(C++11)(C++11) | | to_string(C++11) | | to_wstring(C++11) | | | Literals | | operator""s(C++14) | | Helper classes | | hash<std::basic_string>(C++11) | | Deduction guides (C++17) | |
[edit] | Defined in header <string> |
| template< class CharT, class Traits, class Allocator > std::basic_istream<CharT, Traits>& getline( std::basic_istream<CharT, Traits>& input, std::basic_string<CharT, Traits, Allocator>& str, CharT delim ); | (1) |
| template< class CharT, class Traits, class Allocator > std::basic_istream<CharT, Traits>& getline( std::basic_istream<CharT, Traits>&& input, std::basic_string<CharT, Traits, Allocator>& str, CharT delim ); | (2) | (since C++11) |
| template< class CharT, class Traits, class Allocator > std::basic_istream<CharT, Traits>& getline( std::basic_istream<CharT, Traits>& input, std::basic_string<CharT, Traits, Allocator>& str ); | (3) |
| template< class CharT, class Traits, class Allocator > std::basic_istream<CharT, Traits>& getline( std::basic_istream<CharT, Traits>&& input, std::basic_string<CharT, Traits, Allocator>& str ); | (4) | (since C++11) |
getline reads characters from an input stream and places them into a string:
1,2) Behaves as
UnformattedInputFunction, except that
input.gcount() is not affected. After constructing and checking the sentry object, performs the following:
1) Calls
str.erase().
2) Extracts characters from
input and appends them to
str until one of the following occurs (checked in the order listed)
a) end-of-file condition on
input, in which case, getline sets eofbit.
b) the next available input character is
delim, as tested by
Traits::eq(c, delim), in which case the delimiter character is extracted from
input, but is not appended to
str.
c) str.max_size() characters have been stored, in which case getline sets failbit and returns.
3) If no characters were extracted for whatever reason (not even the discarded delimiter), getline sets failbit and returns.
3,4) Same as
getline(input, str, input.widen('\n')), that is, the default delimiter is the endline character.
Contents - 1 Parameters
- 2 Return value
- 3 Notes
- 4 Example
- 5 Defect reports
- 6 See also
|
[edit] Parameters
| input | - | the stream to get data from |
| str | - | the string to put the data into |
| delim | - | the delimiter character |
[edit] Return value
input
[edit] Notes
When consuming whitespace-delimited input (e.g. int n; std::cin >> n;) any whitespace that follows, including a newline character, will be left on the input stream. Then when switching to line-oriented input, the first line retrieved with getline will be just that whitespace. In the likely case that this is unwanted behaviour, possible solutions include:
- An explicit extraneous initial call to getline.
- Removing consecutive whitespace with std::cin >> std::ws.
- Ignoring all leftover characters on the line of input with cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');.
[edit] Example
The following example demonstrates how to use the getline function to read user input, and to process a stream line by line, or by parts of a line using the delim parameter.
Run this code
#include <iostream> #include <sstream> #include <string> int main
() { // greet the user std::string name
; std::cout << "What is your name? "; std
::getline(std::cin, name
); std::cout << "Hello " << name
<< ", nice to meet you.\n"; // read file line by line std::istringstream input
; input.
str("1\n2\n3\n4\n5\n6\n7\n"); int sum
= 0; for (std::string line
; std
::getline(input, line
);) sum
+= std::stoi(line
); std::cout << "\nThe sum is " << sum
<< ".\n\n"; // use separator to read parts of the line std::istringstream input2
; input2.
str("a;b;c;d"); for (std::string line
; std
::getline(input2, line,
';');) std::cout << line
<< '\n'; } Possible output:
What is your name? John Q. Public Hello John Q. Public, nice to meet you. The sum is 28. a b c d
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
| LWG 91 | C++98 | getline did not behave as an unformatted input function | behaves as an unformatted input function |
[edit] See also
| getline | extracts characters until the given character is found (public member function of std::basic_istream<CharT,Traits>) [edit] |