i want to know code for counting the flashes of LEDs and display no. of flashes in particular time given.by using LDR. basically i tried it with interrupts but i'm not getting it,so please help in this regard.
An hardware solution could be achieved by putting a photodiode or a photoresistance near the flashing LED. Connect it to a pin that supports external interrupt and you're done. With a bit more circuitry you can ensure that the value on the pin doesn't oscillate: put a Schmit Trigger after the photodiode or resitance with its output on the input pin.
LDRs only give an analog output, proportional to the amount of light.
To make it give a HIGH and LOW value, you have to tweak the other resistor used in the voltage divider.
Alternatively you could use
analogRead and add a threshold value in your code.