Compilare: user.cpp: In function ‘void df(int)’: user.cpp:16: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int search(int, int)’: user.cpp:23: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void build()’: user.cpp:35: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void write()’: user.cpp:65: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void read()’: user.cpp:75: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:78: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int search(int, int)’: user.cpp:26: warning: control reaches end of non-void function