led still glowing after the low command

Projects Programming
1 
int a=0;

void setup()
{
pinMode(A5,INPUT);
pinMode(13,OUTPUT);
}

void loop()
{
 a = digitalRead(A5);
 if(a == 1)
 {
   digitalWrite(13,HIGH);
 }
 else
 {
  digitalWrite(13,LOW);
 }
}

i connect 5v pin to A5pin through pushbutton.
when i press the button the led is glowing.
but when i release the button, the led was turning off only after 5 second

2

Use a digital pin as input and use a pullup resistor for the button.

EDIT: Also not that pin 13 is used by the internal LED and that it is used as clock signal for SPI. Maybe another pin would be better.

3

Use a digital pin as input

He already is.

The suggestion to use a pullup resistor for the input is a good one and the easiest way to do it is to use

pinMode(A5, INPUT_PULLUP);

and to change the circuit so that the input is taken to GND (ie LOW) when the button is pressed