請問一C++觀念

[~~~~~~~Jerki~~~~~~~]

C++用函式重載可以增進效率 書上說將此函式指定為friend

我搞不懂一點，為何要多出friend這東西

為何不直接寫在那類別定義中就好呢!?

麻煩各位大大解惑!!先謝謝嚕^^

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