[BUG] `hashing/chaining.cpp` does not compile

[kvedala]

Description

Non compiling code - tried on Windows and GitPod.

gitpod /workspace/C-Plus-Plus $ g++ hashing/chaining.cpp -Wall -o test
hashing/chaining.cpp: In function ‘int main()’:
hashing/chaining.cpp:85:17: error: reference to ‘hash’ is ambiguous
   85 |             h = hash(x, mod);
      |                 ^~~~
In file included from /usr/include/c++/9/bits/basic_string.h:6719,
                 from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from hashing/chaining.cpp:2:
/usr/include/c++/9/bits/functional_hash.h:58:12: note: candidates are: ‘template<class _Tp> struct std::hash’
   58 |     struct hash;
      |            ^~~~
hashing/chaining.cpp:47:5: note:                 ‘int hash(int, int)’
   47 | int hash(int x, int mod) { return x % mod; }
      |     ^~~~
hashing/chaining.cpp:92:17: error: reference to ‘hash’ is ambiguous
   92 |             h = hash(x, mod);
      |                 ^~~~
In file included from /usr/include/c++/9/bits/basic_string.h:6719,
                 from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from hashing/chaining.cpp:2:
/usr/include/c++/9/bits/functional_hash.h:58:12: note: candidates are: ‘template<class _Tp> struct std::hash’
   58 |     struct hash;
      |            ^~~~
hashing/chaining.cpp:47:5: note:                 ‘int hash(int, int)’
   47 | int hash(int x, int mod) { return x % mod; }
      |     ^~~~
hashing/chaining.cpp:98:52: error: reference to ‘hash’ is ambiguous
   98 |             cout << "Hash of " << x << " is = " << hash(x, mod);
      |                                                    ^~~~
In file included from /usr/include/c++/9/bits/basic_string.h:6719,
                 from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from hashing/chaining.cpp:2:
/usr/include/c++/9/bits/functional_hash.h:58:12: note: candidates are: ‘template<class _Tp> struct std::hash’
   58 |     struct hash;
      |            ^~~~
hashing/chaining.cpp:47:5: note:                 ‘int hash(int, int)’
   47 | int hash(int x, int mod) { return x % mod; }
      |     ^~~~
gitpod /workspace/C-Plus-Plus $ 

Original author: @vasutomar

Expected Behavior

Unknown.. no explanation provided anywhere. Should compile at least.

Actual Behavior

Possible Fix

See attached possible fix. But the code does not seem to give expected results.

Steps to Reproduce

1. Open the repo in GitPod using the link provided in the Readme file.
2. From the terminal, issue compilation command as shown in the description above.

Context

Trying to enable CMake auto-configure and compile for files in the folder.

[kvedala]

The issue can be resolved by removing using namespace std;
But this still keeps the issue of

1. using global variables
2. using C-type arrays identified as errors by the CI tools