can I to use this camera like a webcam,what kind of cable I need

This can't be used as a webcam... very few digital cameras can. However, there may be a way to use it as one if you have a TV tuner on your computer. If you have one, check your manual to see if it can be done. If you don't have a TV tuner, it's probably not worthwhile to buy one, as even a cheap one costs $60-$100, and is a hassle to install correctly and get new compatible drivers and whatnot.

Thanks

Robert,

You can't use S3is as a webcam and it's not worth looking for ways and means to make it work as such because for $10 you can buy a proper webcam complete with cables and softwares.

There are many disadvantages of using a digital camera to double up as a webcam and this probably explains why only few cameras have the function.

I have a digital camera that can work as a webcam but never use it besides testing the function once or twice.
My main concern is camera shutter is a delicate part of the camera and it's accuracy is of great importance to ensure that pictures are correctly exposed.

If, by using the camera as a webcam, the shutter has to be kept wide open for hours in a day and several days in a week, by the end of the month, most probably the shutter speed would not be accurate any more. Look upon the $10 webcam as an insurance or whatever to protect your S3is, it's definitely worth investing in a proper webcam than to risk spoilling your S3is.