Compilare: user.cpp: In function ‘void exp()’: user.cpp:9:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<s.length() && s[i-1]!='='; ++i){ ^ user.cpp:38:10: warning: statement has no effect [-Wunused-value] for(i; i<s.length() ; ++i){ ^ user.cpp:38:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i; i<s.length() ; ++i){ ^ user.cpp:41:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i==s.length()-1) ^ user.cpp: In function ‘int main()’: user.cpp:82:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ecuatii2.in", "r", stdin); ^ user.cpp:83:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("output.txt", "w", stdout); ^