The difference between recv and recvfrom

The difference between recv and recvfrom is different parameters, different applicable scenarios, different return values ​​and different data transmission methods. Detailed introduction: 1. The parameters are different. The parameters of the recv function include socket descriptor, receive buffer, data length and flag bit, etc. It is used to receive data from the connected socket. The parameters of the recvfrom function include socket descriptor, Receive buffer, data length, flag bits, target address and address length, etc. It is used to receive data from an unconnected socket and return the sender's address, etc.

recv and recvfrom are two functions commonly used in network programming for receiving data. Their differences are mainly reflected in the following aspects.

1. Different parameters:

- The parameters of the recv function include socket descriptor, receive buffer, data length and flag bit, etc. It is used to receive data from a connected socket.

- The parameters of the recvfrom function include socket descriptor, receive buffer, data length, flag bit, target address and address length, etc. It is used to receive data from an unconnected socket and returns the sender's address.

2. Applicable scenarios are different:

- The recv function is suitable for connected sockets, that is, the connect function needs to be called before using this function. It is commonly used in TCP protocol.

- The recvfrom function is suitable for unconnected sockets, that is, no connection operation is required before using this function. It is commonly used in UDP protocol.

3. The return values ​​are different:

- The recv function returns the length of the received data. If the return value is 0, it means that the other party has closed the connection, and returning -1 means that an error occurred.

- The recvfrom function returns the length of the received data, and saves the sender's address information in the parameters. If the return value is 0, it means that the other party has closed the connection, and returning -1 means that an error occurred.

4. Different data transmission methods:

- The recv function is connection-oriented. It will automatically receive data from the connected socket and maintain the connected state.

- The recvfrom function is connectionless. It needs to specify the address information of the sender every time it receives data.

To sum up, there are some differences between the recv and recvfrom functions in terms of parameters, applicable scenarios, return values ​​and data transmission methods. According to the specific needs and usage scenarios, choosing the appropriate function can better realize the reception of network data.

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