[SOLVED] how to get backspace input from keyboard

rahulvishwakarma · 09-25-2020, 10:56 AM

hi to all, I've mysql server in centos6 server and codeblocks in centos 7client. i am trying to do autofill of

product name when we input some initial letters. this happned but it does not getting back when giving input of

backspace. here is mine code :-

Code:

void product::productSearch()
{
    Get *get = new Get;
    clrscr();
    string prdin = "";
    string prd1 = "";
    int l = get->printMenu(productRecords, "Product Search");
    gotoxy(30, 5);
    //cin >> prdin;
    Getchar *getc;
    char ch;

    MYSQL_ROW row;
    MYSQL_RES *res;
    Conn::conn = Conn::connection();

    do
    {
        ch = getc->getch();
        if(ch == '\b')
        {
            if(prdin.length() > 0)
            {
                prdin = prdin.substr(prdin.length() -1);
            }
        }
        else
        {
            prdin += ch;
        }

        sql = "select productname,stock, rate, productId  from tableProductRecords where productname like '%"+prdin

+"%';";
        int qstate = mysql_query(Conn::conn, sql.c_str());

        if(!qstate)
        {

            res = mysql_store_result(Conn::conn);

            if((row = mysql_fetch_row(res)) != nullptr)
            {
                gotoxy(30, 5);
                cout << row[0];

                gotoxy(30,6);
                cout << row[1];

                gotoxy(30, 7);
                cout << row[2];

                gotoxy(30, 8);
                cout << row[3];
                gotoxy(30 + prdin.length() , 5);
                //ch = getc->getch();
            }
        }
        else
        {
            gotoxy(10, 20);
            cout << "error in product Enter : " << mysql_error(Conn::conn);
        }

    }while(ch != '\n');

    clrscr();
    drawrect();
}

mine getch code is :-

Code:

Read 1 character without echo
getch() function definition.

char Getchar::getch(void)
{
  return getch_(0);
}

void Getchar::initTermios(int echo)
{
  tcgetattr(0, &oldterm); //grab old terminal i/o settings
  newterm = oldterm; //make new settings same as old settings
  newterm.c_lflag &= ~ICANON; //disable buffered i/o
  newterm.c_lflag &= echo ? ECHO : ~ECHO; //set echo mode
  tcsetattr(0, TCSANOW, &newterm); //apply terminal io settings
}

/* Restore old terminal i/o settings */
void Getchar::resetTermios(void)
{
  tcsetattr(0, TCSANOW, &oldterm);
}

SoftSprocket · 09-25-2020, 11:32 AM

If by '\b' you are hoping to catch a backspace you are wrong. '\b' means ring the bell.

You might try

Code:

if (ch == KEY_BACKSPACE)

and have a look at the ncurses manpage for getch.

https://linux.die.net/man/3/getch

SoftSprocket · 09-25-2020, 12:34 PM

Quote:

Originally Posted by SoftSprocket

If by '\b' you are hoping to catch a backspace you are wrong. '\b' means ring the bell.

What was I thinking - \a is the bell (well alert) and \b is backspace but it won't work as expected just the same. The rest of my post does apply.

TB0ne · 09-25-2020, 01:14 PM

Quote:

Originally Posted by rahulvishwakarma

hi to all, I've mysql server in centos6 server and codeblocks in centos 7client. i am trying to do autofill of

product name when we input some initial letters. this happned but it does not getting back when giving input of

backspace. here is mine code :-

Code:

void product::productSearch()
{
    Get *get = new Get;
    clrscr();
    string prdin = "";
    string prd1 = "";
    int l = get->printMenu(productRecords, "Product Search");
    gotoxy(30, 5);
    //cin >> prdin;
    Getchar *getc;
    char ch;

    MYSQL_ROW row;
    MYSQL_RES *res;
    Conn::conn = Conn::connection();

    do
    {
        ch = getc->getch();
        if(ch == '\b')
        {
            if(prdin.length() > 0)
            {
                prdin = prdin.substr(prdin.length() -1);
            }
        }
        else
        {
            prdin += ch;
        }

        sql = "select productname,stock, rate, productId  from tableProductRecords where productname like '%"+prdin

+"%';";
        int qstate = mysql_query(Conn::conn, sql.c_str());

        if(!qstate)
        {

            res = mysql_store_result(Conn::conn);

            if((row = mysql_fetch_row(res)) != nullptr)
            {
                gotoxy(30, 5);
                cout << row[0];

                gotoxy(30,6);
                cout << row[1];

                gotoxy(30, 7);
                cout << row[2];

                gotoxy(30, 8);
                cout << row[3];
                gotoxy(30 + prdin.length() , 5);
                //ch = getc->getch();
            }
        }
        else
        {
            gotoxy(10, 20);
            cout << "error in product Enter : " << mysql_error(Conn::conn);
        }

    }while(ch != '\n');

    clrscr();
    drawrect();
}

mine getch code is :-

Code:

Read 1 character without echo
getch() function definition.

char Getchar::getch(void)
{
  return getch_(0);
}

void Getchar::initTermios(int echo)
{
  tcgetattr(0, &oldterm); //grab old terminal i/o settings
  newterm = oldterm; //make new settings same as old settings
  newterm.c_lflag &= ~ICANON; //disable buffered i/o
  newterm.c_lflag &= echo ? ECHO : ~ECHO; //set echo mode
  tcsetattr(0, TCSANOW, &newterm); //apply terminal io settings
}

/* Restore old terminal i/o settings */
void Getchar::resetTermios(void)
{
  tcsetattr(0, TCSANOW, &oldterm);
}

Really? YOUR getch code??
https://stackoverflow.com/questions/...-linux/7469410

And didn't you ask about something very, VERY similar a few months ago?
https://www.linuxquestions.org/quest...27-4175673488/

Since you've been a member here for ten years, and been coding for that long, you should know to do basic research, and know what '\b' is and does...a non-destructive backspace. Using

Code:

string = sometring.substr(0, somestring.size()-1);

would work. What have you done/tried to get 'your' code working?

rahulvishwakarma · 09-26-2020, 06:37 AM

please tell me how to take input of non-printable ascii chars. such as backspace or enter. or some special keys such as function keys and numpad keys.

TB0ne · 09-26-2020, 08:57 AM

Quote:

Originally Posted by rahulvishwakarma

please tell me how to take input of non-printable ascii chars. such as backspace or enter. or some special keys such as function keys and numpad keys.

Please show effort of your own.

You can read any of the MANY programming guides that tell you how to do this and do basic research on your own. You can find this with a brief Google search, and again...you have been programming for **TEN YEARS** now. Have you not progressed any in an entire decade?? Also curious that you don't comment on 'your' getch code that you posted.

Try this: https://bfy.tw/PBp5

rahulvishwakarma · 09-26-2020, 11:41 AM

i solved my problem via another website. there link as follows :-
https://www.cplusplus.com/forum/beginner/273034/

TB0ne · 09-27-2020, 09:14 AM

Quote:

Originally Posted by rahulvishwakarma

i solved my problem via another website. there link as follows :-
https://www.cplusplus.com/forum/beginner/273034/

Excellent; so you finally were able to look something up for yourself? Great news!