Compilare: user.cpp: In function ‘int main()’: user.cpp:34:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++) ^ user.cpp:43:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(s[i]=='=' || i==s.length()-1) ^ user.cpp:60:52: warning: suggest parentheses around comparison in operand of ‘^’ [-Wparentheses] if(delta>0 && (((int)sqrt(delta))^2==delta)) ^