字符数组和 uintptr_t

Question

I was reading What is uintptr_t data type but still I'm unable to understand uintptr_t here as

• what purpose it serve by first converting temporarily char array type to unsigned long int type and then converting back to char* type.

Consider the below code snapshot

strncpy(pCfgMgr->mGlobalCfg.grMap[index].userName,
       (char *)(uintptr_t) grParams.peerUsrName, 16); /*index is 0 */

where userName in the pCfgMgr->mGlobalCfg.grMap[index].userName is nothing but a char array declared as

char userName[MAX_USERNAME_LENGTH]; /* MAX_USERNAME_LENGTH is 16 */

And peerUsrName in the grParams.peerUsrName is also a char array declared as

char peerUsrName[16];

The thing which I didn't got is that what uintptr_t makes the difference while copying, which is nothing but alias name of unsigned long int . I am curious to know what the developer was thinking while using uintptr_t here & is it recommended ?

Though without uintptr_t above strncpy() statement produces the same output.

All helps appreciated wholeheartedly.

Answer 1

The cast is unnecessary.

The second argument to strncpy has type const char * . An expression of type char * is also valid here. grParams.peerUsrName has type char [16] . Arrays in most contexts decay to a pointer to the first element. So when you pass it to strncpy it decays to type char * , which is what it's expecting. So no need for the cast.