void * typed function parameter

问题

I have a function, void *Client(void *threaData){}

Can you tell me some things about void *threadData parameter. When you use void * parameter and why?

回答1:

void * is a generic pointer which can point to any object type. The above function can take a pointer to any type and can return a pointer to any type.

A generic pointer can be used if it is not sure about the data type of data inputted by the user.

Example: The following function will print any data type provided the user input about the type of data

void funct(void *a, int z)
{
    if(z==1)
        printf("%d",*(int*)a); // If user inputs 1, then he means the data is an integer and type  casting is done accordingly.
    else if(z==2)
        printf("%c",*(char*)a); // Typecasting for character pointer.
    else if(z==3)
        printf("%f",*(float*)a); // Typecasting for float pointer
}

回答2:

Suppose you want to pass an integer to the void *Client(void *threadData){} function, so you would

int integer;

integer = SOME_VALUE;

Client(&integer);

and in the function

void *Client(void *threadData)
{
    int value;

    value = *(int *)threadData;
}

and since void * can be converted to any pointer type, you can pass any data you need to the Client() function.

来源：https://stackoverflow.com/questions/27852372/void-typed-function-parameter