Why does the digital 4 pin have no ~ all the others are ~1 ~2 etc.
It would be unusual for any of those pins to be so-marked - which board are you talking about?
Arduino leonardo.
I have attached a screen shot
all the others are ~1 ~2 etc.
That isn't evident in your photo.
~ denotes a PWM pin.
~ denotes a pin capable of pwm (analogWrite). Pin 4 does not have that capability, and hence has no ~
OP's picture
There's no ~ on 1 and 2 as claimed in the OP.
...and, Oh! Look! It also helpfully says says "PWM~"