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Direct, reference and pointer access to variables
Further C++ Object Oriented features example from a Well House Consultants training course
More on Further C++ Object Oriented features [link]
Source code: sixtyfive.cpp Module: C234
using namespace std;
#include <iostream> /* In C++, you can access variables directly - as I do in the array of ints called number in the following example. Or you may access them as pointers, declared with a * and accessed using * contents of & address of So far ... you can do the same thing in C. But in C++ you can also use references. You declare these with an & and they are essentially aliases to variables - shorthand alternative names, if you like. Once you have set up and used a reference, any changes you make will be to the contents, so you can't realiase them; that makes them less flexible than pointers. However, when a reference goes out of scope at the end of a block, it can then be redefined on the next entry to the block as the alias to another variable. */ main () { int numbers[5]; int k; int * mypointer; numbers[0] =4; numbers[1] =2; numbers[2] =2; numbers[3] =7; numbers[4] =5; // via pointers (flexible but a bit messy) for (k=0; k<5; k++) { mypointer = &numbers[k]; /* & is "address of" */ cout << *mypointer * 17 << endl; } // References are alternative names for variables for (k=0; k<5; k++) { int & myref = numbers[k]; /* & is alternative name */ myref = myref + 15; cout << myref * 17 << endl; } // Straight at variables for (k=0; k<5; k++) { cout << numbers[k] * 17 << endl; } } /* Sample output munchkin:capr grahamellis$ ./sixtyfive 68 34 34 119 85 323 289 289 374 340 323 289 289 374 340 munchkin:capr grahamellis$ */ Learn about this subject
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* Learning to program in C and C++ * C++ for C Programmers * C and C++ Programming * Learning to program in C and C++ * C and C++ Programming Also available on on site courses for larger groups Books covering this topic
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