std::getline - cppreference.com (original) (raw)

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.

1. 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.

[edit] Parameters

[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.

#include #include #include   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.

[edit] See also

| | extracts characters until the given character is found (public member function of std::basic_istream<CharT,Traits>) [edit] | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |