Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Mail Systems
Eclipse Documentation

How To Guides
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Problem Solutions
Privacy Policy




Thinking in C++
Prev Contents / Index Next


If you want to convert from a const to a nonconst or from a volatile to a nonvolatile, you use const_cast. This is the only conversion allowed with const_cast; if any other conversion is involved it must be done using a separate expression or you’ll get a compile-time error.

//: C03:const_cast.cpp
int main() {
  const int i = 0;
  int* j = (int*)&i; // Deprecated form
  j  = const_cast<int*>(&i); // Preferred
  // Can't do simultaneous additional casting:
//! long* l = const_cast<long*>(&i); // Error
  volatile int k = 0;
  int* u = const_cast<int*>(&k);
} ///:~

If you take the address of a const object, you produce a pointer to a const, and this cannot be assigned to a nonconst pointer without a cast. The old-style cast will accomplish this, but the const_cast is the appropriate one to use. The same holds true for volatile.

Thinking in C++
Prev Contents / Index Next

   Reproduced courtesy of Bruce Eckel, MindView, Inc. Design by Interspire