How to Use the Ansi Escape Code for Outputting Colored Text on Console

How to use the ANSI Escape code for outputting colored text on Console

I'm afraid you forgot the ESC character:

#include <cstdio>

int main()
{
    printf("%c[%dmHELLO!\n", 0x1B, 32);
}

Unfortunately it will only work on consoles that support ANSI escape sequences (like a linux console using bash, or old Windows consoles that used ansi.sys)

c++ ansi escape codes not displaying color to console

The problem with reading the config.txt files is that the string is read as though it is assigned to be:

std::string str = "\\033[0;31m";

i.e. the \ is treated as a character. What you need in code is "\033", i.e. the character represented by the octal number 033.

You can change the following lines in your code to ignore the "\\033" part of the string and print the octal number.

    cout << x.second << x.first <<endl;

needs to be:

    cout << '\033' << x.second.substr(4) << x.first <<endl;

With that change, I tried your program on my desktop and it works as expected.

Colored text output in PowerShell console using ANSI / VT100 codes

Note:

• The following applies to regular (legacy) console windows on Windows (provided by conhost.exe), which are used by default, including when a console application is launched from a GUI application.

• By contrast, the console windows (terminals) provided by Windows Terminal provide support for VT / ANSI escape sequences by default, for all console applications.

While console windows in Windows 10 do support VT (Virtual Terminal) / ANSI escape sequences in principle, support is turned OFF by default.

You have three options:

• (a) Activate support globally by default, persistently, via the registry, as detailed in this SU answer.

  • In short: In registry key [HKEY_CURRENT_USER\Console], create or set the VirtualTerminalLevel DWORD value to 1
    
    • From PowerShell, you can do this programmatically as follows:
      
      Set-ItemProperty HKCU:\Console VirtualTerminalLevel -Type DWORD 1
    • From cmd.exe (also works from PowerShell):
      
      reg add HKCU\Console /v VirtualTerminalLevel /t REG_DWORD /d 1
  • Open a new console window for changes to take effect.
  • See caveats below.

• (b) Activate support from inside your program, for that program (process) only, with a call to the SetConsoleMode() Windows API function.

  • See details below.

• (c) Ad-hoc workaround, from PowerShell: pipe output from external programs to Out-Host; e.g., .\test.exe | Out-Host

  • See details below.

Re (a):

The registry-based approach invariably activates VT support globally, i.e., for all console windows, irrespective of what shell / program runs in them:

• Individual executables / shells can still deactivate support for themselves, if desired, using method (b).

• Conversely, however, this means that the output of any program that doesn't explicitly control VT support will be subject to interpretation of VT sequences; while this is generally desirable, hypothetically this could lead to misinterpretation of output from programs that accidentally produce output with VT-like sequences.

Note:

• While there is a mechanism that allows console-window settings to be scoped by startup executable / window title, via subkeys of [HKEY_CURRENT_USR\Console], the VirtualTerminalLevel value seems not to be supported there.

• Even if it were, however, it wouldn't be a robust solution, because opening a console window via a shortcut file (*.lnk) (e.g. from the Start Menu or Task Bar) wouldn't respect these settings, because *.lnk files have settings built into them; while you can modify these built-in settings via the Properties GUI dialog, as of this writing the VirtualTerminalLevel setting is not surfaced in that GUI.

Re (b):

Calling the SetConsoleMode() Windows API function from inside the program (process), as shown here, is cumbersome even in C# (due to requiring P/Invoke declarations), and may not be an option:

• for programs written in languages from which calling the Windows API is not supported.

• if you have a preexisting executable that you cannot modify.

In that event, option (c) (from PowerShell), discussed next, may work for you.

Re (c):

PowerShell automatically activates VT (virtual terminal) support for itself when it starts (in recent releases of Windows 10 this applies to both Windows PowerShell and PowerShell (Core) 7+) - but that does not extend to external programs called from Windows PowerShell. but does when called from PowerShell (Core) as of at least 7.2.

• Separately, in v7.2+ there is the $PSStyle.OutputRendering preference variable, which controls whether PowerShell commands produce colored output via the formatting system, such as the colored headers of Get-ChildItem output. However, this setting has no effect on (direct) output from external programs. $PSStyle.OutputRendering defaults to Host, meaning that only formatted output that prints to the terminal (console) is colored. $PSStyle.OutputRendering = 'PlainText' disables coloring, and $PSStyle.OutputRendering = 'Ansi' makes it unconditional; see this answer for more information.

However, as a workaround for Windows PowerShell you can relay an external program's output via a PowerShell command, in which case VT sequences are recognized; using Out-Host is the simplest way to do that (Write-Host would work too):

.\test.exe | Out-Host

Note: Use Out-Host only if you mean to print to the console; if, by contrast, you want to capture the external program's output, use just $capturedOutput = .\test.exe

Alternatively, you can enclose the call in (...), which, however, invariably collects all output first, before relaying it.

(.\test.exe)

Character-encoding caveat: Windows PowerShell by default expects output from external programs to use the OEM code page, as defined by the legacy system locale (e.g., 437 on US-English systems) and as reflected in [console]::OutputEncoding.
.NET console programs respect that setting automatically, but for non-.NET programs (e.g., Python scripts) that use a different encoding (and produce not just pure ASCII output (in the 7-bit range)), you must (at least temporarily) specify that encoding by assigning to [console]::OutputEncoding; e.g., for UTF-8:

[console]::OutputEncoding = [Text.Encoding]::Utf8.

Note that this is not only necessary for the VT-sequences workaround, but generally necessary for PowerShell to interpret non-ASCII characters correctly.

PowerShell Core (v6+), unfortunately, as of v7.3, still defaults to the OEM code page too, but that should be considered a bug, given that it otherwise defaults to UTF-8 without BOM.

List of ANSI color escape sequences

The ANSI escape sequences you're looking for are the Select Graphic Rendition subset. All of these have the form

\033[XXXm

where XXX is a series of semicolon-separated parameters.

To say, make text red, bold, and underlined (we'll discuss many other options below) in C you might write:

printf("\033[31;1;4mHello\033[0m");

In C++ you'd use

std::cout<<"\033[31;1;4mHello\033[0m";

In Python3 you'd use

print("\033[31;1;4mHello\033[0m")

and in Bash you'd use

echo -e "\033[31;1;4mHello\033[0m"

where the first part makes the text red (31), bold (1), underlined (4) and the last part clears all this (0).

As described in the table below, there are a large number of text properties you can set, such as boldness, font, underlining, &c.

Font Effects

 var stdout = Console.OpenStandardOutput();
 var con = new StreamWriter(stdout, Encoding.ASCII);
 con.AutoFlush = true;
 Console.SetOut(con);

 Console.WriteLine("\x1b[36mTEST\x1b[0m");