Compilare: user.cpp: In function ‘int main()’: user.cpp:75:19: warning: unused variable ‘w’ [-Wunused-variable] int n,i,j,k=0,w,x,gr; ^ user.cpp:75:21: warning: unused variable ‘x’ [-Wunused-variable] int n,i,j,k=0,w,x,gr; ^ user.cpp:84:20: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s,cst,in); n=strlen(s); ^