Compilare: user.cpp: In function ‘void write()’: user.cpp:12:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) ^ user.cpp: In function ‘void read()’: user.cpp:33:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) ^ user.cpp: In function ‘void qs(std::vector<int>&)’: user.cpp:59:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < x.size() / 2; i++) ^ user.cpp:65:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < z.size() / 2; i++) ^ user.cpp: In function ‘void read()’: user.cpp:27:36: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result] system("pabcnetc.exe rand.pas"); ^ user.cpp:28:23: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result] system("rand.exe"); ^ user.cpp:38:39: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result] system("del rand.exe rand.o rand"); ^