Defined in header <iomanip> | ||
---|---|---|
/*unspecified*/ setw( int n ); |
When used in an expression out << setw(n)
or in >> setw(n)
, sets the width
parameter of the stream out
or in
to exactly n
.
n | - | new value for width |
Returns an object of unspecified type such that if str
is the name of an output stream of type std::basic_ostream<CharT, Traits>
or std::basic_istream<CharT, Traits>
, then the expression str << setw(n)
or str >> setw(n)
behaves as if the following code was executed:
str.width(n);
The width property of the stream will be reset to zero (meaning "unspecified") if any of the following functions are called:
basic_ostream::operator<<()
(at Stage 3 of num_put::put()
) operator<<(basic_ostream&, char)
and operator<<(basic_ostream&, char*)
operator<<(basic_ostream&, basic_string&)
std::put_money
(inside money_put::put()
) std::quoted
(when used with an output stream) The exact effects this modifier has on the input and output vary between the individual I/O functions and are described at each operator<<
and operator>>
overload page individually.
#include <sstream> #include <iostream> #include <iomanip> int main() { std::cout << "no setw:" << 42 << '\n' << "setw(6):" << std::setw(6) << 42 << '\n' << "setw(6), several elements: " << 89 << std::setw(6) << 12 << 34 << '\n'; std::istringstream is("hello, world"); char arr[10]; is >> std::setw(6) >> arr; std::cout << "Input from \"" << is.str() << "\" with setw(6) gave \"" << arr << "\"\n"; }
Output:
no setw:42 setw(6): 42 setw(6), several elements: 89 1234 Input from "hello, world" with setw(6) gave "hello"
manages field width (public member function of std::ios_base ) |
|
changes the fill character (function template) |
|
sets the placement of fill characters (function) |
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http://en.cppreference.com/w/cpp/io/manip/setw