Symbolic constants in C++

[Code Apperentice]

How do you define symbolic constants like in C in C++? Also, are there such things as foreach in C++? If yes, how to implement it?

[TwilightSpectre]

Yes, and Yes. For symbolic constants, there are two main ways. Either you could use a #define like in C, or you could simply declare the variable as either const or constepr.

As for foreach, it does exist. There are two versions of it:

#include <vector>
#include <algorithm>
#include <iostream>

int main() {
    // a container
    std::vector<int> vec {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    // version 1: Range-based for
    for (int i : vec) {
        std::cout << i << ' ';
    }
    std::cout << '\n';

    // version 2: std::for_each
    std::for_each(vec.begin(), vec.end(), [](int i){ std::cout << i << ' '; });

    return 0;
}

[Catfish666]

Code Apprentice wrote:

How do you define symbolic constants like in C in C++?

The same way, by #define'ing them.
However as a C++ programmer you are encouraged to use constants instead.

// old-fashioned C/C++ code
#define PI 3.141593

// "the right way" C++ code
const double PI = 3.141593;

Code Apprentice wrote:

Also, are there such things as foreach in C++?

As of C++11 (the C++ standard of year 2011) there is the range-based for() loop, which can act as a foreach() loop.

Example code (will compile on Visual Studio 2013, GNU GCC 4.7+):

std::vector<int> vi {1, 3, 100};

// range-based for() loop to print all elements of vi
for (int i: vi)
    std::cout << i << '\n';

// range-based for() loop to set all elements of vi to 13
for (int &i: vi)
    i = 13;

http://www.icce.rug.nl/documents/cplusplus/cplusplus03.html#l42

Code Apprentice wrote:

If yes, how to implement it?

Before C++11, the Boost library implemented it as BOOST_FOREACH():

http://www.boost.org/doc/libs/1_55_0/doc/html/foreach.html
http://cplusplus.bordoon.com/boost_foreach_techniques.html

[Code Apperentice]

Ty all