Int is the basic integer type in all systems, which is generally 32 bits, that is to say, it can store numbers ranging from -32768 to 32767.

Long usually takes up more storage space than int and is used to store larger numbers than int can store.

Moreover, short generally takes up less space than int, and int is used to save smaller numbers to save space.

Books recommend "C++ Primer". You can go to Baidu Library:

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All right, that's all. You can ask me again if you have any questions:-D.