Which C++ function changes text or background color (MS Visual studio)? For example cout<<\"This text\"; how to make \"This text\" red color.
Colour isn't a C++ thing, but a property of your terminal. If your terminal speaks ANSI (e.g. any Linux terminal, or DOS or Windows NT if you add DEVICE=C:\DOS\ansi.sys to your config.sys, or later Windows if you call the shell with cmd.exe /kansicon), then you can try the following gimmick:
#define ANSI_COLOR_RED "\x1b[31m"
#define ANSI_COLOR_GREEN "\x1b[32m"
#define ANSI_COLOR_YELLOW "\x1b[33m"
#define ANSI_COLOR_BLUE "\x1b[34m"
#define ANSI_COLOR_MAGENTA "\x1b[35m"
#define ANSI_COLOR_CYAN "\x1b[36m"
#define ANSI_COLOR_BRIGHT "\x1b[1m"
#define ANSI_COLOR_RESET "\x1b[0m"
std::cout << ANSI_COLOR_RED "Hello World\n" ANSI_COLOR_RESET;
Wikipedia has a list of ANSI escape sequences.