{"id":1790,"date":"2025-01-24T22:36:18","date_gmt":"2025-01-24T22:36:18","guid":{"rendered":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/?page_id=1790"},"modified":"2025-01-25T17:41:15","modified_gmt":"2025-01-25T17:41:15","slug":"stream-output","status":"publish","type":"page","link":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/topics\/c-details\/i-o-streams\/stream-output\/","title":{"rendered":"Stream Output"},"content":{"rendered":"\n

<\/span>Stream Output<\/span><\/h2>\n\n\n\n

The ostream<\/strong> class provides both formatted and unformatted output:<\/p>\n\n\n\n

    \n
  • Output of standard data types with the stream-insertion operator<\/em><\/li>\n\n\n\n
  • Output of characters with the put<\/strong> member function<\/li>\n\n\n\n
  • Unformatted output with the write<\/strong> member function<\/li>\n\n\n\n
  • Output of integers in decimal, octal, and hexadecimal formats<\/li>\n\n\n\n
  • Output of floating point values with various precisions, with forced decimal points, in scientific notation and in fixed notation<\/li>\n\n\n\n
  • Output of data justified in fields of specified field widths<\/li>\n\n\n\n
  • Output of data in fields padded with specified characters<\/li>\n\n\n\n
  • Specification of uppercase letters in scientific notation and in hexadecimal notation.<\/li>\n<\/ul>\n\n\n\n

    <\/span>Stream-Insertion Operator<\/span><\/h3>\n\n\n\n

    Stream output may be performed using the stream-insertion operator<\/em>:<\/p>\n\n\n\n

    <\/span>The overloaded << operator<\/span><\/h4>\n\n\n\n

    The operator is overloaded to provide type-safe output of built-in types (int<\/strong>, char<\/strong>, long<\/strong>, short<\/strong>, unsigned<\/strong>, double<\/strong>, float<\/strong>, etc., plus string types and pointer values)<\/p>\n\n\n\n

    For example:<\/p>\n\n\n\n

    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"This is C++ output!<\/span>\\n<\/span>"<\/span>;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"This is more C++ "<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"output...<\/span>\\n<\/span>"<\/span>;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which outputs:<\/p>\n\n\n\n
    This is C++ output!\nThis is more C++ output...\nProgram ended with exit code: 0\n<\/code><\/pre>\n<\/div>\n<\/div>\n\n\n\n
    <\/span>endl<\/strong> and flush<\/strong> Stream Manipulators<\/span><\/h4>\n\n\n\n
    You can also use the endl<\/strong> and flush<\/strong> stream manipulators:<\/p>\n\n\n\n
    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"This is C++ output!"<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>std<\/span>::endl;<\/span>  \/\/ outputs newline and flushes<\/span><\/span>\n  <\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"This is more C++ output!"<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>std<\/span>::flush;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which outputs:<\/p>\n\n\n\n
    This is C++ output!\nThis is more C++ output!Program ended with exit code: 0\n<\/code><\/pre>\n\n\n\n
    \n
    flush<\/code> is used to force any data still in the buffer to be output.<\/p>\n<\/blockquote>\n<\/div>\n<\/div>\n\n\n\n
    You can use whole expressions:<\/p>\n\n\n\n
    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>int<\/span> a = <\/span>5<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"a + 5 = "<\/span> << a + <\/span>5<\/span> << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which outputs:<\/p>\n\n\n\n
    a + 5 = 10\nProgram ended with exit code: 0\n<\/code><\/pre>\n<\/div>\n<\/div>\n\n\n\n
    But you have to be careful with precedence<\/em>:<\/p>\n\n\n\n
    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>int<\/span> a = <\/span>5<\/span>;<\/span><\/span>\n  <\/span>int<\/span> b = <\/span>7<\/span>;<\/span><\/span>\n  <\/span>int<\/span> c = <\/span>9<\/span>;<\/span><\/span>\n    <\/span><\/span>\n  \/\/ But be careful about precedence:<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"a^b|c = "<\/span> << (a^b|c) << <\/span>std<\/span>::endl;<\/span> \/\/ Compile-time error<\/span><\/span>\n  <\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"a^b|c = "<\/span> << ( (a^b) |c) << <\/span>std<\/span>::endl;<\/span> \/\/ OK<\/span><\/span>\n<\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which produces a compile-time warning:<\/p>\n\n\n\n
    main.cpp:17:32 '^' within '|'\n\nPlace parentheses around the '^' expression to silence this warning\n<\/code><\/pre>\n<\/div>\n<\/div>\n\n\n\n
    … and associativity:<\/p>\n\n\n\n
    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>int<\/span> a = <\/span>5<\/span>;<\/span><\/span>\n  <\/span>int<\/span> b = <\/span>7<\/span>;<\/span><\/span>\n<\/span>\n  \/\/ Problem with associativity:<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"a<<b = "<\/span> << a<<b << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  \/\/ What we probably meant:<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"a<<b = "<\/span> << (a<<b) << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which outputs:<\/p>\n\n\n\n
    a<<b = 57\na<<b = 640\nProgram ended with exit code: 0<\/code><\/pre>\n<\/div>\n<\/div>\n\n\n\n
    You can output null-terminated strings, from a string literal, or using references to a character array, or a pointer to a string literal:<\/p>\n\n\n\n
    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>std<\/span>::cout << <\/span>"Hello world!"<\/span> << <\/span>std<\/span>::endl;<\/span><\/span>\n<\/span>\n  <\/span>char<\/span> buffer[] = <\/span>"Bonjour, le monde!"<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << buffer << <\/span>std<\/span>::endl;<\/span><\/span>\n<\/span>\n  <\/span>char<\/span> *ptr = <\/span>"Wilkommen in das Weld!"<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << ptr << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>const<\/span> <\/span>char<\/span> *ptr2 = <\/span>"Ciao mondo!"<\/span>;<\/span><\/span>\n  <\/span>std<\/span>::cout << ptr2 << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which outputs:<\/p>\n\n\n\n
    Hello world!\nBonjour, le monde!\nWilkommen in das Weld!\nCiao mondo!\nProgram ended with exit code: 0<\/code><\/pre>\n\n\n\n
    But note the compile-time warning:<\/p>\n\n\n\n
    main.cpp:17:15 ISO C++11 does not allow conversion from string literal to 'char *'<\/code><\/pre>\n\n\n\n
    Solved by adding a const:<\/p>\n\n\n\n
    const char *ptr2 = \"Ciao mondo!\";<\/code><\/pre>\n<\/div>\n<\/div>\n\n\n\n
    <\/span>char * vs void * Overloading for the << Operator<\/span><\/h4>\n\n\n\n
    Note that there is a special overloading of the stream-insertion operator for char*<\/strong> types. <\/p>\n\n\n\n
    \n
    \n
    <\/path><\/path><\/svg><\/span>
    \/\/<\/span><\/span>\n\/\/  main.cpp<\/span><\/span>\n\/\/  ostream<\/span><\/span>\n\/\/<\/span><\/span>\n\/\/  Created by Bryan Higgs on 9\/2\/24.<\/span><\/span>\n\/\/<\/span><\/span>\n<\/span>\n#include<\/span> <\/span><iostream><\/span><\/span>\n<\/span>\nint<\/span> <\/span>main<\/span>(<\/span>int<\/span> <\/span>argc<\/span>, <\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span> <\/span>argv<\/span>[]) <\/span><\/span>\n{<\/span><\/span>\n  <\/span>int<\/span> i = <\/span>5<\/span>;<\/span><\/span>\n  <\/span>int<\/span> *int_ptr = &i;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>std<\/span>::cout << int_ptr << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>const<\/span> <\/span>char<\/span> *char_ptr = <\/span>"This is C++"<\/span>;<\/span><\/span>\n<\/span>\n  <\/span>std<\/span>::cout << char_ptr << <\/span>std<\/span>::endl;<\/span><\/span>\n  <\/span><\/span>\n  <\/span>std<\/span>::cout << (<\/span>void<\/span>*) char_ptr << <\/span>std<\/span>::endl;<\/span><\/span>\n<\/span>\n  <\/span>return<\/span> <\/span>0<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n<\/div>\n\n\n\n
    \n
    which outputs:<\/p>\n\n\n\n
    0x7ff7bfeff12c\nThis is C++\n0x100003f30\nProgram ended with exit code: 0<\/code><\/pre>\n\n\n\n
    Most pointer types output the contents of the pointer<\/em>, not what it points to. <\/p>\n\n\n\n
    But char * outputs the string that the pointer points to. If you want the value of the pointer itself, you must explicitly cast the pointer to void *<\/em>.<\/p>\n\n\n\n
    \n
    Note the addition of ‘const’ to avoid the compile-time warning.<\/p>\n<\/blockquote>\n<\/div>\n<\/div>\n\n\n\n
    <\/span>The put<\/strong> Member Function<\/span><\/h3>\n\n\n\n
    There is also the overloaded put member function defined for class ostream<\/strong>:<\/p>\n\n\n\n
    cout.put('A');<\/strong><\/code><\/pre>\n\n\n\n
    where the argument may be a char<\/strong>, unsigned<\/strong> char<\/strong>, or signed<\/strong> char<\/strong>.<\/p>\n\n\n\n
    Calls to put<\/strong> may be concatenated:<\/p>\n\n\n\n
    cout.put('A\u2019).put('\\n');<\/strong><\/code><\/pre>\n\n\n\n
    because the dot (.<\/strong>) operator, like the <<<\/strong> operator, associates from left to right.<\/p>\n\n\n\n
    <\/div>\n\n\n\n
    \n
    Next: Stream Input<\/a><\/div>\n<\/div>\n\n\n\n
    <\/p>\n","protected":false},"excerpt":{"rendered":"
    Stream Output The ostream class provides both formatted and unformatted output: Stream-Insertion Operator Stream output may be performed using the stream-insertion operator: The overloaded << operator The operator is overloaded to provide type-safe output of built-in types (int, char, long, short, unsigned, double, float, etc., plus string types and pointer values) For example: which outputs: […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":936,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1790","page","type-page","status-publish","hentry"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/pages\/1790","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/comments?post=1790"}],"version-history":[{"count":8,"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/pages\/1790\/revisions"}],"predecessor-version":[{"id":1825,"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/pages\/1790\/revisions\/1825"}],"up":[{"embeddable":true,"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/pages\/936"}],"wp:attachment":[{"href":"https:\/\/bhiggs.x10hosting.com\/PracticalCPlusPlusProgramming\/index.php\/wp-json\/wp\/v2\/media?parent=1790"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}