Set point with keypad 4x4

Hello everyone, I want to make a temperature control program using Arduino Uno, DS18B20 sensor, LCD 16x2, 4x4 keypad and relay. temperature sensor ds18b20 to detect temperature inside the box and I want to use the 4x4 keypad to set the temperature set point value, which is displayed on lcd 16x2, after that the relay will be active, if the temperature in the box exceeds the set point value we have set using the 4x4 keypad , the relay will turn off. please help me make a setpoint program using the 4x4 keypad, I hope you can help me complete my task. thank you, have a nice day.

Have been able to get each component working by itself with a simple test program for each part?

Exactly. I suggest starting with the LCD display and try to get the famous "hello world" sketch working. It is a bit easier if the LCD has an I2C backpack.
How much time have you got for this assignment ? There is quite some work there.

Post#1 and Post#2 have given you proper guidelines on how to proceed with the project implementation. This post is an addition to the above two – just a variant.

1. This is the overall connection diagram on drawing board of the various components of your project.
Figure-1: Connection diagram

2. Now follow SSS (Small Start Strategy) approach and finish the project.
(1) Connect only the Keypad and check that when you enter 24.75 from the Keypad, the same figure also appears on the Serial Monitor. Take help from IDE Example; but, try to follow the connection diagram of Fig-1. Please, post your codes to get help if the codes are not working. (But, there is no point (.) in the Keypad; how to enter the point? We can map the asterisk (*) label of the Keypad as point (.) by the following definition:(Edit))

const byte rows = 4;   //four rows
const byte cols = 4;  //four columns
char keys[rows][cols] = {   //2-dimensional array contains ASCII codesfor the labels of Keys
                          {'.','0','#','D'}     //point (.) is added in place of *

byte rowPins[rows] = {2, 3, 4, 5}; //R1R2R3R4 connection Pin = 2 3 4 5
byte colPins[cols] = {6,7, 8, 9};  //C1C2C3C4 connection Pin = 6 7 8 9
Keypad myKeypad = Keypad(makeKeymap(keys),rowPins,colPins,rows,cols);  //Library Function

(2) Connect I2CLCD and repeat Step-(1) to see that 24.75 appears on LCD.

(3) Connect DS18B20 and show the temperature on Serial Monitor at 1-sec interval. This is the functional check of the sensor.

(4) Connect the relay and devise a control program based on the codes of Steps-(1) to (3) so that the relay gets activated when the set-point is met.

(But, there is no point (.) in the Keypad; how to enter the point? We can map the asterisk (*) label of the Keypad as point (.) by the following definition:)

That's a very significant edit over what was there before. In the 10 hours between your (GolamMostafa's) post and the edit, the OP may have read what was there before, and not see the change next time he or she comes to the thread. Unmarked edits are surely for fixing spelling mistakes etc. not for significant content updates.

But to my point: @OP, the entering of a number such as xxx.yyy or even the integer xxx is not covered in the keypad library examples. It's not difficult, but nor is it trivial, and there are a few examples around. At least, I found examples of how to do an integer xxx and I wrote code for the decimal part .yyy also . When you get to the stage of capturing the number, you'll see what I mean. Right now it probably seems to you that you would just type 123*456 and have a float 123.456. Not quite as trivial as that.

So get the keypad library installed and running, understand how it works. Then look into how to finesse the input to be xxx.yyy; we'll cross that particular hurdle then. Right now, not having a . on the keypad is the very least of your problems, I'd say.

That's a very significant edit over what was there before.

I acknowledge, appreciate, and accept your remark with great honor and dignity. I should have added the word Edit. My initial plan was not adding the point (.) in the Key-matrix definition; but as time was passing out and there was no response from the OP, I decided to add the point in the definition with a hope that it might facilitate the OP to solve his problem.