/in/foo.cc: In function 'int main()':
/in/foo.cc:18:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i = 0; i <= str.length(); i++)
~~^~~~~~~~~~~~~~~
/in/foo.cc:21:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if(i == str.length() || str[i] == '+' || str[i] == '*')
~~^~~~~~~~~~~~~~~
/in/foo.cc:26:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if(i != str.length())
~~^~~~~~~~~~~~~~~