Compilare: main.cpp: In function 'int main()': main.cpp:59:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~ main.cpp:75:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i + 1 == s.size() || s[i + 1] == '+' || s[i + 1] == '-') { ~~~~~~^~~~~~~~~~~ main.cpp:45:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("eq4.in", "r", stdin); ^ main.cpp:46:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("eq4.out", "w", stdout); ^