What is the difference between condition variables and semaphores in C++?

What is the difference between condition variables and semaphores in C++?

Condition variables and semaphores are both synchronization primitives used in multithreading, but they serve different purposes. Condition variables are used for signaling between threads, allowing one thread to wait for a condition to be met by another thread. Semaphores, on the other hand, are used to control access to a shared resource by maintaining a count of available resources.

Can you give an example of how to use a condition variable?

Sure! Here's a simple example: You have a producer thread that produces data and a consumer thread that consumes it. The consumer can wait on a condition variable until the producer signals that data is available. This prevents the consumer from checking continuously and wasting CPU resources.

What about semaphores? How do they work?

Semaphores maintain a count that represents the number of available resources. When a thread wants to access a resource, it decrements the semaphore. If the count is zero, the thread will block until a resource becomes available. When a thread releases a resource, it increments the semaphore, potentially waking up a blocked thread.

Which one should I use in my project?

It depends on your specific use case. If you need to signal between threads and wait for conditions, use condition variables. If you need to manage access to a limited number of resources, semaphores are the way to go.