c++ - 使用 mmap() 时从 'void*' 到 'char*' 的无效转换

Question

我有以下片段:

char* filename;
unsigned long long int bytesToTransfer;
int fd, pagesize;
char *data;

fd = open(filename, O_RDONLY);
if (fd==NULL){
    fputs ("File error",stderr);
    exit (1);
}

cout << "File Open: " << filename << endl;

pagesize = getpagesize();
data = mmap((caddr_t)0, bytesToTransfer, PROT_READ, MAP_SHARED, fd, 0);
if (*data == -1) {
    fputs ("Memory error",stderr);
    exit (2);
}

cout << "Data to Send: " << data << endl;

但是当我编译时，我收到:

error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive] data = mmap((caddr_t)0, bytesToTransfer, PROT_READ, MAP_SHARED, fd, 0);

有人可以提示我哪里出了问题吗？

Answer 1

C++ 不执行来自void* 的隐式转换，您必须将此显式化

data = static_cast<char*>(mmap((caddr_t)0, bytesToTransfer, PROT_READ, MAP_SHARED, fd, 0));