malloc returns a void pointer to the allocated space, or NULL if there is insufficient memory available. To return a pointer to a type other than void, use a type cast on the return value. The storage space pointed to by the return value is guaranteed to be suitably aligned for storage of any type of object. If size is 0, malloc allocates a zero-length item in the heap and returns a valid pointer to that item. Always check the return from malloc, even if the amount of memory requested is small.

malloc 返回一個(gè)指向已分配空間的 void 指針，如果內(nèi)存不足，則返回 NULL。若要返回指向非 void 類型的指針，請(qǐng)?jiān)诜祷刂瞪鲜褂妙愋娃D(zhuǎn)換。由返回值指向的存儲(chǔ)空間保證適當(dāng)?shù)貙?duì)齊以存儲(chǔ)任何類型的對(duì)象。如果 size 是 0，malloc 會(huì)在堆中分配一個(gè)零長(zhǎng)度的項(xiàng)目，并返回一個(gè)指向該項(xiàng)目的有效指針。即使請(qǐng)求的內(nèi)存量很小，也要始終檢查 malloc 的返回值。

在動(dòng)態(tài)分配內(nèi)存是的時(shí)候失敗了