please suggest me.............

You are limited by the subnet range.

If you have a consumer based router, many of them are limited by one subnet with a /24 mask. You can then only have 254 usable IPs behind that router for your hosts.

So it depends.

JorgeM is correct, except that normally it would be 253 IP's since the router gateway address will take at least one (usually 1 or 254) as 0 and 255 are special cases and aren't used for node id's.

Here is a good Wikipedia article on the subject:

I am thinking about wi-fi

how much computers can connect to an wireless network?

give me some specific details about how many computers can connect to a specific router.

The answer is the same. It depends on the subnet. For a typical home implementation using a /24 mask, 252 hosts (1 for the router and one for the access point). However, keep in mind that wireless is a shared network like classic Ethernet. The more nodes you have on the wireless AP, the slower the network becomes.

I've heard some routeur has a limitation for computer connection. Not beacause of subnet. I don't know is that true or not.

Which limifation are you referring to? Only connecting to one computer? If that's true, which I haven't seen, it would be a feature limitation, not an IP or router limitation. Maybe you are thinking about a modem that an ISP may be using like in the old days where you could only connect one host and you would have to run PPPoE software on the pc to establish the connection back to your ISP.

I believe that pssingh1001's question has nothing to do with subnetting... it's more related to router's resource like procie and memory capacity...
so, my answer is it depends on how large your the bandwidth is, and how busy the network is...

there are many other things which consume the resources;
- PPS (packet per second), this will push the processor to work harder as PPS increase.
- Network mode (NAT, Routing, Bridge); since bridged-mode works in layer 2 (data link) it will work faster and free the processor from hard work in handling every single packet of data; while NAT has heavier job for the processor since all packet's header need to be translated then to be route...
- Wifi Encryption: your wifi devices will have to work heavier with encryption enabled (WEP, WPA/WPA2) because the devices must create unique encryption keys for the communication between the device and the clients...