Using a 3x4 matrix keypad with I2C LCD

Alright that would make sense but how would i setup for attemptC such as

char attemptC[8]={
0,0,0,0,0,0,0,0};

and also how i would i display it on the LCD when i enter in the code such as if i typed "12345678" into the keypad it displays "Turn Red On?" before i actually press enter?
Thank You