if (T2==0){PORTD = 0b00000000;PORTC = 0b00011000;}
if (T2==1){PORTD = 0b11100100;PORTC = 0b00011000;}
if (T2==2){PORTD = 0b10010000;PORTC = 0b00010000;}
if (T2==3){PORTD = 0b11000000;PORTC = 0b00010000;}
if (T2==4){PORTD = 0b01100100;PORTC = 0b00010000;}
if (T2==5){PORTD = 0b01001000;PORTC = 0b00010000;}
if (T2==6){PORTD = 0b00001000;PORTC = 0b00010000;}
if (T2==7){PORTD = 0b11100000;PORTC = 0b00011000;}
if (T2==8){PORTD = 0b00000000;PORTC = 0b00010000;}
if (T2==9){PORTD = 0b01000000;PORTC = 0b00010000;}
Clearly, this should be in a function, displayTensValue(int val).
if (T1==0)PORTB = 0b11111111;
if (T1==1)PORTB = 0b11111001;
if (T1==2)PORTB = 0b11100100;
if (T1==3)PORTB = 0b11110000;
if (T1==4)PORTB = 0b11010001;
if (T1==5)PORTB = 0b11010010;
if (T1==6)PORTB = 0b11000010;
if (T1==7)PORTB = 0b11111000;
if (T1==8)PORTB = 0b11000000;
if (T1==9)PORTB = 0b11010000;
Clearly, this should be in a function, displayOnesValue(int val).
The bulk of the second sketch deals with splitting a two digit int, obtained from a function with the lousy name of serial_readdbl() into the tens value and the ones value, and displaying those digits on the hardware.
The first sketch gets the temperature from the thermometer, as a two digit int, most likely, and then uses am unnecessarily complex process to convert that integer value to a string that looks like a float value.
Once you have Temp, from the first sketch, call the functions from the second sketch to split the number into a ones value and a tens value, and display those values on the hardware.
When is our homework due?