#include <string>
#include <vector>

using namespace std;

int main() {
    vector<string> a;
    a.push_back("foo");
    a[0] == NULL;
    return 0;
}

a.cpp: In function 'int main()':
a.cpp:9:10: error: no match for 'operator==' (operand types are 'std::__cxx11::basic_string<char>' and 'long long int')
     a[0] == NULL;
          ^
In file included from C:/mingw-w64/x86_64-5.1.0-posix-seh-rt_v4-rev0/mingw64/x86_64-w64-mingw32/include/c++/bits/stl_algobase.h:64:0,
                 from C:/mingw-w64/x86_64-5.1.0-posix-seh-rt_v4-rev0/mingw64/x86_64-w64-mingw32/include/c++/bits/char_traits.h:39,
                 from C:/mingw-w64/x86_64-5.1.0-posix-seh-rt_v4-rev0/mingw64/x86_64-w64-mingw32/include/c++/string:40,

a.cpp:9:10: error: invalid operands to binary expression ('std::__cxx11::basic_string<char>' and 'int')
    a[0] == NULL;
    ~~~~ ^  ~~~~
C:\mingw-w64\x86_64-5.1.0-posix-seh-rt_v4-rev0\mingw64\x86_64-w64-mingw32\include\c++\bits/stl_pair.h:214:5: note: candidate template ignored: could not match 'pair' against 'basic_string'
    operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
    ^
C:\mingw-w64\x86_64-5.1.0-posix-seh-rt_v4-rev0\mingw64\x86_64-w64-mingw32\include\c++\bits/stl_iterator.h:292:5: note: candidate template ignored: could not match 'reverse_iterator' against 'bas…

C:\Users\Brian\Desktop\Temp>g++ -Wall -O3 -march=haswell -o a.exe a.cpp
a.cpp:10:2: error: expected declaration before '}' token
 }}}
  ^

C:\Users\Brian\Desktop\Temp>clang++ -Wall -O3 -march=haswell -o a.exe a.cpp
a.cpp:10:2: error: extraneous closing brace ('}')
}}}
 ^
a.cpp:10:3: error: extraneous closing brace ('}')
}}}
  ^
2 errors generated.

C:\Users\Brian\Desktop\Temp>g++ -Wall -O3 -march=haswell -o a.exe a.cpp
a.cpp: In function 'int main()':
a.cpp:7:13: warning: suggest parentheses around assignment used as truth value [
-Wparentheses]
     if(i = 0)
             ^

C:\Users\Brian\Desktop\Temp>clang++ -Wall -O3 -march=haswell -o a.exe a.cpp
a.cpp:7:10: warning: using the result of an assignment as a condition without
      parentheses [-Wparentheses]
    if(i = 0)
       ~~^~~
a.cpp:7:10: note: place parentheses around the assignment to silence this