<iomanip> functions

Visual Studio 2015
 

The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.

The latest version of this topic can be found at <iomanip> functions.

lt;iomanip> get_money](#iomanip_get_money)|<iomanip> get_time|<iomanip> put_money|
|<iomanip> put_time|quoted|resetiosflags|
|setbase|setfill|setiosflags|
|setprecision|setw|

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.

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.

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.

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.

(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  
*/  
  

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.

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.

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.

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.

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.

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  

<iomanip>

Show: