为什么我不能引用以前转换为void的字符串中的字符？

Question

To use pthreads, I used as input a char* that was cast to void* as input. If it's later cast to (char*) it can be printed and used normally ( (char*)var ). However, if one does (char*)var[i], where 'i' will help us reference a character, it doesn't. Why?

eg MS says 'expression must be a pointer to a complete object type'.

Answer 1

Because of operator precedence: the cast comes after the subscript operator.

You have to write ((char*)var)[i]; .

Answer 2

The cast, in this case, is lower precedence than the array indexing. Instead, you would have to do something like *((char *)var + i) , but the clearest approach is probably to assign it to a temporary:

 char *str = var;
 printf("%c", str[i]);

Answer 3

Try (char *) &var[i] , but that simply gets reference from var[i] . You can't do (char *) var[i] as that actually tries to convert a char to (char *) .