Difference between revisions of "cpp/io/manip/left"

Latest revision as of 22:36, 15 September 2023

Defined in header `<ios>`
std::ios_base& left( std::ios_base& str );	(1)
std::ios_base& right( std::ios_base& str );	(2)
std::ios_base& internal( std::ios_base& str );	(3)

Modifies the positioning of the fill characters in an output stream. left and right apply to any type being output, internal applies to integer, floating-point, and monetary output. Has no effect on input.

1) Sets the adjustfield of the stream str to left as if by calling str.setf(std::ios_base::left, std::ios_base::adjustfield).

2) Sets the adjustfield of the stream str to right as if by calling str.setf(std::ios_base::right, std::ios_base::adjustfield).

3) Sets the adjustfield of the stream str to internal as if by calling str.setf(std::ios_base::internal, std::ios_base::adjustfield).

The initial default for standard streams is equivalent to right.

This is an I/O manipulator. It may be called with an expression such as out << std::left for any out of type std::basic_ostream or with an expression such as in >> std::left for any in of type std::basic_istream.

#include <iomanip>
#include <iostream>
#include <locale>
 
int main()
{
    std::cout.imbue(std::locale("en_US.utf8"));
 
    std::cout << "Default positioning:\n" << std::setfill('*')
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << std::hex << std::showbase << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << "\n\n";
 
    std::cout << "Left positioning:\n" << std::left
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << "\n\n";
 
    std::cout << "Internal positioning:\n" << std::internal
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << "\n\n";
 
    std::cout << "Right positioning:\n" << std::right
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << '\n';
}

Output:

Default positioning:
*******-1.23
********0x2a
***USD *1.23
 
Left positioning:
-1.23*******
0x2a********
USD *1.23***
 
Internal positioning:
-*******1.23
0x********2a
USD ****1.23
 
Right positioning:
*******-1.23
********0x2a
***USD *1.23

[edit] See also

setw	changes the width of the next input/output field (function) [edit]
setfill	changes the fill character (function template) [edit]
showbasenoshowbase	controls whether prefix is used to indicate numeric base (function) [edit]

@@ Line 1: / Line 1: @@
 {{cpp/title|left|right|internal}}
 {{cpp/io/manip/navbar}}
-{{ddcl list begin}}
+{{dcl begin}}
-{{ddcl list header|ios}}
+{{dcl header|ios}}
-{{ddcl list item | num = 1|
+{{dcl|num=1|
 std::ios_base& left( std::ios_base& str );
 }}
-{{ddcl list item | num = 2|
+{{dcl|num=2|
 std::ios_base& right( std::ios_base& str );
 }}
-{{ddcl list item | num = 3|
+{{dcl|num=3|
 std::ios_base& internal( std::ios_base& str );
 }}
-{{ddcl list end}}
+{{dcl end}}
-Modifies the default positioning of the fill characters. {{tt|left}} and {{tt|right}} apply to any output, {{tt|internal}} applies to integer, floating-point, and monetary output. Has no effect on input.
+Modifies the positioning of the fill characters in an output stream. {{tt|left}} and {{tt|right}} apply to any type being output, {{tt|internal}} applies to integer, floating-point, and monetary output. Has no effect on input.
-) sets the {{tt|adjustfield}} of the stream {{tt|str}} to {{tt|left}} as if by calling {{c|str.setf(std::ios_base::left, std::ios_base::adjustfield)}}
+@1@ Sets the {{tt|adjustfield}} of the stream {{c|str}} to {{tt|left}} as if by calling {{c|str.setf(std::ios_base::left, std::ios_base::adjustfield)}}.
-) sets the {{tt|adjustfield}} of the stream {{tt|str}} to {{tt|right}} as if by calling {{c|str.setf(std::ios_base::right, std::ios_base::adjustfield)}}
+@2@ Sets the {{tt|adjustfield}} of the stream {{c|str}} to {{tt|right}} as if by calling {{c|str.setf(std::ios_base::right, std::ios_base::adjustfield)}}.
-) sets the {{tt|adjustfield}} of the stream {{tt|str}} to {{tt|internal}} as if by calling {{c|str.setf(std::ios_base::internal, std::ios_base::adjustfield)}}
+@3@ Sets the {{tt|adjustfield}} of the stream {{c|str}} to {{tt|internal}} as if by calling {{c|str.setf(std::ios_base::internal, std::ios_base::adjustfield)}}.
-This is an I/O manipulator, it may be called with an expression such as {{c|out << std::left}} for any {{tt|out}} of type {{c|std::basic_ostream}} or with an expression such as {{c|in >> std::left}} for any {{tt|in}} of type {{c|std::basic_istream}}.
+The initial default for standard streams is equivalent to {{tt|right}}.
+This is an I/O manipulator. It may be called with an expression such as {{c|out << std::left}} for any {{tt|out}} of type {{lc|std::basic_ostream}} or with an expression such as {{c|in >> std::left}} for any {{tt|in}} of type {{lc|std::basic_istream}}.
 ===Parameters===
-{{param list begin}}
+{{par begin}}
-{{param list item | str | reference to I/O stream }}
+{{par|str|reference to I/O stream}}
-{{param list end}}
+{{par end}}
 ===Return value===
+{{c|str}} (reference to the stream after manipulation).
-{{tt|str}} (reference to the stream after manipulation)
 ===Example===
 {{example
- |
+|code=
- | code=
-#include <iostream>
 #include <iomanip>
+#include <iostream>
 #include <locale>
 int main()
 {
      std::cout.imbue(std::locale("en_US.utf8"));
-     std::cout << "Left fill:\n" << std::left << std::setfill('*')
+     std::cout << "Default positioning:\n" << std::setfill('*')
                << std::setw(12) << -1.23  << '\n'
                << std::setw(12) << std::hex << std::showbase << 42 << '\n'
+              << std::setw(12) << std::put_money(123, true) << "\n\n";
+    std::cout << "Left positioning:\n" << std::left
+              << std::setw(12) << -1.23  << '\n'
+              << std::setw(12) << 42 << '\n'
                << std::setw(12) << std::put_money(123, true) << "\n\n";
-     std::cout << "Internal fill:\n" << std::internal
+     std::cout << "Internal positioning:\n" << std::internal
                << std::setw(12) << -1.23  << '\n'
                << std::setw(12) << 42 << '\n'
                << std::setw(12) << std::put_money(123, true) << "\n\n";
-     std::cout << "Right fill:\n" << std::right
+     std::cout << "Right positioning:\n" << std::right
                << std::setw(12) << -1.23  << '\n'
                << std::setw(12) << 42 << '\n'
                << std::setw(12) << std::put_money(123, true) << '\n';
 }
- | output=
+|output=
-Left fill:
+Default positioning:
+*******-1.23
+********0x2a
+***USD *1.23
+Left positioning:
 -1.23*******
 x2a********
 USD *1.23***
-Internal fill:
+Internal positioning:
 -*******1.23
 x********2a
 USD ****1.23
-Right fill:
+Right positioning:
 *******-1.23
 ********0x2a
@@ Line 76: / Line 88: @@
 ===See also===
-{{dcl list begin}}
+{{dsc begin}}
-{{dcl list template | cpp/io/manip/dcl list setw}}
+{{dsc inc|cpp/io/manip/dsc setw}}
-{{dcl list template | cpp/io/manip/dcl list setfill}}
+{{dsc inc|cpp/io/manip/dsc setfill}}
-{{dcl list end}}
+{{dsc inc|cpp/io/manip/dsc showbase}}
+{{dsc end}}
+{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

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Difference between revisions of "cpp/io/manip/left"

Latest revision as of 22:36, 15 September 2023

Contents

[edit] Parameters

[edit] Return value

[edit] Example

[edit] See also

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