<iomanip> functions
The latest version of this topic can be found at <iomanip> functions.
| get_money | get_time | put_money |
| put_time | quoted | resetiosflags |
| setbase | setfill | setiosflags |
| setprecision | setw |
<iomanip> get_money
Extracts a monetary value from a stream using the desired format, and returns the value in a parameter.
template <class Money>
T7 get_money(
Money& _Amount,
bool _Intl);
Parameters
_Amount
The extracted monetary value.
_Intl
If true, use international format. The default value is false.
Remarks
The manipulator returns an object that, when extracted from the stream str, behaves as a formatted input function that calls the member function get for the locale facet money_get associated with str, using _Intl to indicate international format. If successful, the call stores in _Amount the extracted monetary value. The manipulator then returns str.
Money must be of type long double or an instantiation of basic_string with the same element and traits parameters as str.
<iomanip> get_time
Extracts a time value from a stream using a desired format. Returns the value in a parameter as a time structure.
template <class Elem>
T10 put_time(
struct tm *_Tptr,
const Elem *_Fmt);
Parameters
_Tptr
The time in the form of a time structure.
_Fmt
The desired format to use to obtain the time value.
Remarks
The manipulator returns an object that, when extracted from the stream str, behaves as a formatted input function that calls the member function get for the locale facet time_get associated with str, using tptr to indicate the time structure and fmt to indicate the beginning of a null-terminated format string. If successful, the call stores in the time structure the values associated with any extracted time fields. The manipulator then returns str.
<iomanip> put_money
Inserts a monetary amount using the desired format into a stream.
template <class Money>
T8 put_money(
const Money& _Amount,
bool _Intl);
Parameters
_Amount
The monetary amount to insert into the stream.
_Intl
Set to true if manipulator should use international format, false if it should not.
Return Value
Returns str.
Remarks
The manipulator returns an object that, when inserted into the stream str, behaves as a formatted output function that calls the member function put for the locale facet money_put associated with str. If successful, the call inserts amount suitably formatted, using _Intl to indicate international format and str.fill(), as the fill element. The manipulator then returns str.
Money must be of type long double or an instantiation of basic_string with the same element and traits parameters as str.
<iomanip> put_time
Writes a time value from a time structure to a stream by using a specified format.
template <class Elem>
T10 put_time(
struct tm* _Tptr,
const Elem* _Fmt);
Parameters
_Tptr
The time value to write to the stream, provided in a time structure.
_Fmt
The desired format to write the time value.
Remarks
The manipulator returns an object that, when inserted into the stream str, behaves as a formatted output function. The output function calls the member function put for the locale facet time_put associated with str. The output function uses _Tptr to indicate the time structure and _Fmt to indicate the beginning of a NUL-terminated format string. If successful, the call inserts literal text from the format string and converted values from the time structure. The manipulator then returns str.
quoted
(New in C++14) An iostream manipulator that enables convenient round-tripping of strings into and out of streams using the >> and << operators.
quoted(std::string str) // or wstring
quoted(const char* str) //or wchar_t*
quoted(std::string str,
char delimiter,
char escape) // or wide versions
quoted(const char* str,
char delimiter,
char escape) // or wide versions
Parameters
str
A std::string, char*, string literal or raw string literal, or a wide version of any of these (e.g. std::wstring, wchar_t*).
delimiter
A user-specified character, or wide character, to use as the delimiter for the beginning and end of the string.
escape
A user-specified character, or wide character, to use as the escape character for escape sequences within the string.
Remarks
See Using Insertion Operators and Controlling Format.
Example
This example shows how to use quoted with the default delimiter and escape character using narrow strings. Wide strings are equally supported.
#include <iostream>
#include <iomanip>
#include <sstream>
using namespace std;
void show_quoted_v_nonquoted()
{
// Results are identical regardless of input string type:
// string inserted { R"(This is a "sentence".)" }; // raw string literal
// string inserted { "This is a \"sentence\"." }; // regular string literal
const char* inserted = "This is a \"sentence\"."; // const char*
stringstream ss, ss_quoted;
string extracted, extracted_quoted;
ss << inserted;
ss_quoted << quoted(inserted);
cout << "ss.str() is storing : " << ss.str() << endl;
cout << "ss_quoted.str() is storing: " << ss_quoted.str() << endl << endl;
// Round-trip the strings
ss >> extracted;
ss_quoted >> quoted(extracted_quoted);
cout << "After round trip: " << endl;
cout << "Non-quoted : " << extracted << endl;
cout << "Quoted : " << extracted_quoted << endl;
}
void main(int argc, char* argv[])
{
show_quoted_v_nonquoted();
// Keep console window open in debug mode.
cout << endl << "Press Enter to exit" << endl;
string input{};
getline(cin, input);
}
/* Output:
ss.str() is storing : This is a "sentence".
ss_quoted.str() is storing: "This is a \"sentence\"."
After round trip:
Non-quoted : This
Quoted : This is a "sentence".
Press Enter to exit
*/
Example
The following example shows how to provide custom a delimiter and/or escape character:
#include <iostream>
#include <iomanip>
#include <sstream>
using namespace std;
void show_custom_delimiter()
{
string inserted{ R"("This" "is" "a" "heavily-quoted" "sentence".)" };
// string inserted{ "\"This\" \"is\" \"a\" \"heavily-quoted\" \"sentence\"" };
// const char* inserted{ "\"This\" \"is\" \"a\" \"heavily-quoted\" \"sentence\"" };
stringstream ss, ss_quoted;
string extracted;
ss_quoted << quoted(inserted, '*');
ss << inserted;
cout << "ss_quoted.str() is storing: " << ss_quoted.str() << endl;
cout << "ss.str() is storing : " << ss.str() << endl << endl;
// Use the same quoted arguments as on insertion.
ss_quoted >> quoted(extracted, '*');
cout << "After round trip: " << endl;
cout << "Quoted : " << extracted << endl;
extracted = {};
ss >> extracted;
cout << "Non-quoted : " << extracted << endl << endl;
}
void show_custom_escape()
{
string inserted{ R"(\\root\trunk\branch\nest\egg\yolk)" };
// string inserted{ "\\\\root\\trunk\\branch\\nest\\egg\\yolk" };
stringstream ss, ss_quoted, ss_quoted_custom;
string extracted;
// Use '"' as delimiter and '~' as escape character.
ss_quoted_custom << quoted(inserted, '"', '~');
ss_quoted << quoted(inserted);
ss << inserted;
cout << "ss_quoted_custom.str(): " << ss_quoted_custom.str() << endl;
cout << "ss_quoted.str() : " << ss_quoted.str() << endl;
cout << "ss.str() : " << ss.str() << endl << endl;
// No spaces in this string, so non-quoted behaves same as quoted
// after round-tripping.
}
void main(int argc, char* argv[])
{
cout << "Custom delimiter:" << endl;
show_custom_delimiter();
cout << "Custom escape character:" << endl;
show_custom_escape();
// Keep console window open in debug mode.
cout << endl << "Press Enter to exit" << endl;
string input{};
getline(cin, input);
}
/* Output:
Custom delimiter:
ss_quoted.str() is storing: *"This" "is" "a" "heavily-quoted" "sentence".*
ss.str() is storing : "This" "is" "a" "heavily-quoted" "sentence".
After round trip:
Quoted : "This" "is" "a" "heavily-quoted" "sentence".
Non-quoted : "This"
Custom escape character:
ss_quoted_custom.str(): "\\root\trunk\branch\nest\egg\yolk"
ss_quoted.str() : "\\\\root\\trunk\\branch\\nest\\egg\\yolk"
ss.str() : \\root\trunk\branch\nest\egg\yolk
Press Enter to exit
*/
resetiosflags
Clears the specified flags.
T1 resetiosflags(ios_base::fmtflags _Mask);
Parameters
_Mask
The flags to clear.
Return Value
The manipulator returns an object that, when extracted from or inserted into the stream str, calls str. setf( ios_base::fmtflags, _ Mask), and then returns str.
Example
See setw for an example of using resetiosflags.
setbase
Set base for integers.
T3 setbase(int _Base);
Parameters
_Base
The number base.
Return Value
The manipulator returns an object that, when extracted from or inserted into the stream str, calls str. setf( mask, ios_base::basefield), and then returns str. Here, mask is determined as follows:
If _ Base is 8, then mask is
ios_base::oct.If _ Base is 10, then mask is
ios_base::dec.If _ Base is 16, then mask is
ios_base::hex.If _ Base is any other value, then mask is
ios_base::fmtflags(0).
Example
See setw for an example of using setbase.
setfill
Sets the character that will be used to fill spaces in a right-justified display.
template <class Elem>
T4 setfill(Elem _Ch);
Parameters
_Ch
The character that will be used to fill spaces in a right-justified display.
Return Value
The template manipulator returns an object that, when extracted from or inserted into the stream str, calls str. fill( _Ch), and then returns str. The type Elem must be the same as the element type for the stream str.
Example
See setw for an example of using setfill.
setiosflags
Sets the specified flags.
T2 setiosflags(ios_base::fmtflags _Mask);
Parameters
_Mask
The flags to set.
Return Value
The manipulator returns an object that, when extracted from or inserted into the stream str, calls str. setf(_ Mask), and then returns str.
Example
See setw for an example of using setiosflags.
setprecision
Sets the precision for floating-point values.
T5 setprecision(streamsize _Prec);
Parameters
_Prec
The precision for floating-point values.
Return Value
The manipulator returns an object that, when extracted from or inserted into the stream str, calls str. precision( _Prec), and then returns str.
Example
See setw for an example of using setprecision.
setw
Specifies the width of the display field for the next element in the stream.
T6 setw(streamsize _Wide);
Parameters
_Wide
The width of the display field.
Return Value
The manipulator returns an object that, when extracted from or inserted into the stream str, calls str. width(_ Wide), then returns str.
Remarks
setw sets the width only for the next element in the stream and must be inserted before each element whose width you want to specify.
Example
// iomanip_setw.cpp
// compile with: /EHsc
// Defines the entry point for the console application.
//
// Sample use of the following manipulators:
// resetiosflags
// setiosflags
// setbase
// setfill
// setprecision
// setw
#include <iostream>
#include <iomanip>
using namespace std;
const double d1 = 1.23456789;
const double d2 = 12.3456789;
const double d3 = 123.456789;
const double d4 = 1234.56789;
const double d5 = 12345.6789;
const long l1 = 16;
const long l2 = 256;
const long l3 = 1024;
const long l4 = 4096;
const long l5 = 65536;
int base = 10;
void DisplayDefault( )
{
cout << endl << "default display" << endl;
cout << "d1 = " << d1 << endl;
cout << "d2 = " << d2 << endl;
cout << "d3 = " << d3 << endl;
cout << "d4 = " << d4 << endl;
cout << "d5 = " << d5 << endl;
}
void DisplayWidth( int n )
{
cout << endl << "fixed width display set to " << n << ".\n";
cout << "d1 = " << setw(n) << d1 << endl;
cout << "d2 = " << setw(n) << d2 << endl;
cout << "d3 = " << setw(n) << d3 << endl;
cout << "d4 = " << setw(n) << d4 << endl;
cout << "d5 = " << setw(n) << d5 << endl;
}
void DisplayLongs( )
{
cout << setbase(10);
cout << endl << "setbase(" << base << ")" << endl;
cout << setbase(base);
cout << "l1 = " << l1 << endl;
cout << "l2 = " << l2 << endl;
cout << "l3 = " << l3 << endl;
cout << "l4 = " << l4 << endl;
cout << "l5 = " << l5 << endl;
}
int main( int argc, char* argv[] )
{
DisplayDefault( );
cout << endl << "setprecision(" << 3 << ")" << setprecision(3);
DisplayDefault( );
cout << endl << "setprecision(" << 12 << ")" << setprecision(12);
DisplayDefault( );
cout << setiosflags(ios_base::scientific);
cout << endl << "setiosflags(" << ios_base::scientific << ")";
DisplayDefault( );
cout << resetiosflags(ios_base::scientific);
cout << endl << "resetiosflags(" << ios_base::scientific << ")";
DisplayDefault( );
cout << endl << "setfill('" << 'S' << "')" << setfill('S');
DisplayWidth(15);
DisplayDefault( );
cout << endl << "setfill('" << ' ' << "')" << setfill(' ');
DisplayWidth(15);
DisplayDefault( );
cout << endl << "setprecision(" << 8 << ")" << setprecision(8);
DisplayWidth(10);
DisplayDefault( );
base = 16;
DisplayLongs( );
base = 8;
DisplayLongs( );
base = 10;
DisplayLongs( );
return 0;
}
default display
d1 = 1.23457
d2 = 12.3457
d3 = 123.457
d4 = 1234.57
d5 = 12345.7
setprecision(3)
default display
d1 = 1.23
d2 = 12.3
d3 = 123
d4 = 1.23e+003
d5 = 1.23e+004
setprecision(12)
default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789
setiosflags(4096)
default display
d1 = 1.234567890000e+000
d2 = 1.234567890000e+001
d3 = 1.234567890000e+002
d4 = 1.234567890000e+003
d5 = 1.234567890000e+004
resetiosflags(4096)
default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789
setfill('S')
fixed width display set to 15.
d1 = SSSSS1.23456789
d2 = SSSSS12.3456789
d3 = SSSSS123.456789
d4 = SSSSS1234.56789
d5 = SSSSS12345.6789
default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789
setfill(' ')
fixed width display set to 15.
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789
default display
d1 = 1.23456789
d2 = 12.3456789
d3 = 123.456789
d4 = 1234.56789
d5 = 12345.6789
setprecision(8)
fixed width display set to 10.
d1 = 1.2345679
d2 = 12.345679
d3 = 123.45679
d4 = 1234.5679
d5 = 12345.679
default display
d1 = 1.2345679
d2 = 12.345679
d3 = 123.45679
d4 = 1234.5679
d5 = 12345.679
setbase(16)
l1 = 10
l2 = 100
l3 = 400
l4 = 1000
l5 = 10000
setbase(8)
l1 = 20
l2 = 400
l3 = 2000
l4 = 10000
l5 = 200000
setbase(10)
l1 = 16
l2 = 256
l3 = 1024
l4 = 4096
l5 = 65536