What do you mean by polling in single threading in c?

Answer 1

When you are polling for data, you constantly check the variable in a loop of some sort to detect changes.

For example:

volatile int x = 10; //some other thread will change poll

while (x > 5);

This is a very simple example of polling. Another thread is suppose to change poll from 10 to something else. In the current thread the above excerpt is running, the while loop constantly "polls" the variable x and the thread will never move on from the while loop. Polling can be used for seen when monitoring sensors, IO streams, and other things.

Polling eats up CPU cycles and normally should be avoided in favor of other methods in most cases.