LED Blinking Using Push button Whenever I upload the following program I am getting error message 
showing "expected initializer before interval".

Kindly Help me to solve out this probleme.

const byte button=2;
const byte LED=10;
bool blinking =false;//defines when blinking should occur
unsigned long blink Interval=250;// number of milliseconds for blink
unsigned long currentMillis;// variables to track millis()
unsigned long previousMillis;
void setup()
{
    pinMode(button,INPUT);
    pinMode(LED,OUTPUT);
}
void loop()
{
    // this code  blinks the LED
    if(blinking) {
        currentMillis =millis();// better to store in variable, for less jitter

        if((unsignedlong)(currentMillis-previousMillis) &gt;=blinkInterval) { // enough time passed yet?
            digitalWrite(LED,!digitalRead(LED)); // shortcut to toggle the LED
            previousMillis =currentMillis;// sets the time we wait "from"
        }
    } else {
        digitalWrite(LED,LOW); // force LED off when not blinking
    }

    int reading=digitalRead(button);
    delay(50); // crude de-bouncing

    if(reading==LOW) // buttons with pull-up are pressed when LOW
    { blinking =true; }// start blinking
    else
    { blinking =false; }// stop blinking
}
It is blinkInterval, not blink Interval. You have an space in the name in the declaration:

unsigned long blinkInterval=250; // number of milliseconds for blink
// ....
if((unsigned long)(currentMillis-previousMillis) &gt;= blinkInterval) {