Const itself is defined for constants, such as
Const int buffsize = 512;
So can this constant are referenced by an integer pointer, such as int * ptr = & buffsize;
Due to the limitations of the compiler (which cannot be tracked in any point pointing, this requires data stream analysis), this compilation cannot be passed. So, this is to define a constant pointer: const int * ptr;
Constants can be cited with constant pointers, but cannot be modified. At the same time, constant pointers can also point to variables, but cannot modify this variable by pointer: PTR = & buffsize; // ok
INT size = 16; PTR = & size; // ok * ptr = 17; // Will Cause An Error
It can be seen that the constant pointer is for the amount of Const.
Now turn over and see this function definition: int strcmp (const char * str1, const char * str2); what does it mean? In the actual program, pointing to the pointer of Const as a formal parameter, which is guaranteed as an agreement that the actual object passed to the function will not be modified in the program.
Finally, if you want to define a complete constant pointer? As follows: Const Double Pi = 3.14159265; Const Double * Const PTR = & PI;
A Related Reference: / ************** Begin of constptr.cpp ****************** /
#include
INT Main (int Argc, char * argv []) {const Double pi = 3.14158265; const double * ptr;
PTR = & PI;
COUT << "The value of pointer /" ptr / "is" << * Ptr << ENDL;
Double Radius = 3.0; Double Area = PI * RADIUS * RADIUS;
PTR = & area;
COUT << "The value of pointer /" ptr / "is" << * Ptr << ENDL;
/ ******* TEST Const Ptr *********** / Const Double * const p2 = & pi;
COUT << "The value of p2 is" << * p2 << Endl;
/ * P2 = & area; // Will Cause An Error Here Cout << "The value of p2 is" << * p2 << Endl; * /
Return 0;}
/ ************** * endof constptr.cpp ***************** // ******************* ****** Build: g -o constptr constptr.cpp ******* /
