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Unveiling the Intricacies of std::flush: A Comprehensive Perspective
What is std::flush?
std::flush is a member function of the std::ostream class that serves as a manipulator. It ensures that any pending output in the stream's buffer is flushed immediately. This operation forces the data to be written to the external destination.
When to Use std::flush
The decision to flush a stream depends on the specific scenario. Here are some common situations:
Importance of Flushing
Flushing streams ensures data integrity and consistency. Consider the following scenario: a program is writing data to a file without flushing. In case of a system crash, the data stored in the buffer may be lost, leaving the file incomplete. Flushing prevents such data loss by forcing the data to be written to the destination promptly.
Implementation Details
std::flush internally calls std::ostream::flush(), which in turn invokes std::streambuf::pubsync(). This function is responsible for emptying the buffer associated with the stream and sending the data to the external destination.
Performance Considerations
Buffering data before writing to the destination can improve performance significantly. Writing a large number of characters individually takes considerably longer than writing them in batches. std::flush optimizes this process by gathering data and writing it in bulk when it reaches a certain threshold or when explicitly requested.
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