Compilare: main.cpp: In function 'int read_int()': main.cpp:48:35: warning: array subscript has type 'char' [-Wchar-subscripts] while(!isDigit[c = read_char()] && c != '-'); ^ main.cpp:56:20: warning: array subscript has type 'char' [-Wchar-subscripts] while(isDigit[c]) ^ main.cpp: In function 'std::__cxx11::string read_string()': main.cpp:70:34: warning: array subscript has type 'char' [-Wchar-subscripts] while(isDigit[c = read_char()]) ^ main.cpp: In function 'bool cmp(const int&, const int&)': main.cpp:90:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < op[a].str.size(); i++) ~~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:140:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j < vd[i].size(); j++) ~~^~~~~~~~~~~~~~ main.cpp: In function 'char read_char()': main.cpp:21:54: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer, sizeof(char), BUFFER_SIZE, fin); ^