How to write an "Echo Server"?

[zsdz]

Sample 8 can enable the usbkeyboard,and echo the typed letter on screen

I want to write an "Echo Server",when user typed a line,the server will echo the while line,so I change the sample 8 code:

declare

char s[100];

in class CKernel

then

 void CKernel::KeyPressedHandler (const char *pString)
 {
     s_pThis->m_Screen.Write (pString, strlen (pString));

    if(pString[0]!='\n')
    {
	    strcat(s_pThis->s,pString);
    }
    else
    {
	    strcat(s_pThis->s,pString);
            s_pThis->m_Screen.Write (s_pThis->s, strlen (s_pThis->s));
	    strcpy(s_pThis->s,"");
    }
}

and add

strcpy(s_pThis->s,"");

in function

boolean CKernel::Initialize (void)

before

return bOK;

if got key not equal '\n',strcat it,else write it on screen and clear the buffer.

the prog works fine,but I write it in the call-back function KeyPressedHandler.I want write the logic in the "main function",in circle it should be the

TShutdownMode CKernel::Run (void)

function,like write

 scanf(line)
 printf(line)

in c,I can write it in the main function.After all I can't always put the logic code in the call-back function

How to do this?Thanks!

[rsta2]

There is a class CConsole, which allows to input a line via an USB keyboard or other device with echo.

scanf() and printf() is not available in Circle itself, but the circle-stdlib project adds it to Circle. You can also use fgets() with it to read a line from the keyboard.

[zsdz]

Thanks!I try to learn CConsole by sample 32 as the doc said,but when I finish make,and start the rpi4.I got only an stationary cursor on the left top of screen.I have connect the usbkeyboard.Do I have to connect an I2c device?I have connect a 1602 screen by i2c

[rsta2]

Normally there should be at least some log lines on the HDMI display from initialization, and this can only happen, when there is a cmdline.txt file on the SD card with a logdev=ttyS1 option inside. An I2C device does not need to be connected, so that this normally works.