foo.cpp: In function 'std::vector<int> highPrecisionMulti(std::vector<int>, std::vector<int>)':
foo.cpp:56:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < num2.size(); i++){
                    ^
foo.cpp:61:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < num1.size(); j++){
                     ^
foo.cpp:70:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < sum.size(); i++){
                    ^
foo.cpp: In function 'int main()':
foo.cpp:108:23: error: 'strlen' was not declared in this scope
  int n = strlen(number);
                       ^
foo.cpp:112:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < result.size(); i++){
                    ^