Compilare: user.cpp: In function ‘void calculeaza_arie()’: user.cpp:113: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void afisare()’: user.cpp:121: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:138: warning: comparison between signed and unsigned integer expressions user.cpp:141: warning: comparison between signed and unsigned integer expressions user.cpp:154: warning: comparison between signed and unsigned integer expressions user.cpp:157: warning: comparison between signed and unsigned integer expressions