arduino and seven segment with two digit
Guessing about what the problem is you're facing as you don't give enough details.

int val = 0;
val = analogRead(analogPin);    // read the input pin
int temp= val*5 ; //calculating the voltage
temp /= 1024 ;    //calculating the voltage
temp = (temp) * 100 ;// as 1V/100c


You are using integer math, for Arduino this means both val and temp are whole numbers ranging from -32768 to +32767.

You read a value from ADC, this value ranges from 0-1023 and you did not set the reference voltage. This means that reading 0 equals GND / 0V and reading 1023 equals +Vdd = 5V (approx. varying with your power supply, possibly being USB).

Say your supply voltage is 5V and the voltage at the input pin is 0.7V. The analogRead(analogPin); will return 1024 × 0.7 / 5 = 143.

Next you multiply that number: 143 × 5 = 715, so far so good.

Then you divide this number by 1024, this is where your program goes wrong: 715 / 1024 = 0.689 but we are doing integer math, and integers hold whole numbers only and all numbers after the decimal point will be chopped off! So temp is 0 at this point. It doesn't matter how much you multiply the result from this point, it will always be 0.

Change int temp to float temp, that should solve your issue. It instructs the compiler not to use integers, but to use a floating number instead.

There is an error here too:

int tempL; //low number
tempL=int(temp*10);
int tempH;//high number
tempH=int(temp/10);


Change it to:

int tempH;//high number
tempH=int(temp/10);
int tempL; //low number
tempL=int(temp-tempH*10);