Main.cc: In function ‘int main()’: Main.cc:31:11: error: cannot convert ‘std::vector’ to ‘int’ for argument ‘1’ to ‘void t(int, int)’ t(c[i],9); ^ Main.cc:33:18: error: no matching function for call to ‘reverse(std::vector&)’ if(reverse(c[i])){ ^ Main.cc:13:6: note: candidate: bool reverse(char*) bool reverse(char s[]){ ^~~~~~~ Main.cc:13:6: note: no known conversion for argument 1 from ‘std::vector’ to ‘char*’ In file included from /usr/include/c++/7/algorithm:62:0, from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:65, from Main.cc:1: /usr/include/c++/7/bits/stl_algo.h:1180:5: note: candidate: template void std::reverse(_BIter, _BIter) reverse(_BidirectionalIterator __first, _BidirectionalIterator __last) ^~~~~~~ /usr/include/c++/7/bits/stl_algo.h:1180:5: note: template argument deduction/substitution failed: Main.cc:33:18: note: candidate expects 2 arguments, 1 provided if(reverse(c[i])){ ^