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C - C++ Threads - Important Considerations - Thread function arguments are always pass by value

NOTE: Arguments are always copies into the internal storage for threads.

Any changes made by the thread to the arguments passed does not affect the original arguments.

Example

#include <iostream>
#include <string>
#include <thread>
#include <functional>
 
 
void ChangeTotal(std::int& targetTotal)
{
  targetTotal = 20;
  std::cout << " Changing target_total to " << targetTotal << std::endl;
}
 
int main()
{
  int total = 10;
  std::thread t1(ChangeTotal, total);
  t1.join();
  std::cout << "Current Total is " << total << std::endl;
  return 0;
}