Compilare: user.cpp: In function ‘int main()’: user.cpp:20:10: warning: variable ‘a’ set but not used [-Wunused-but-set-variable] char a; ^ user.cpp:23:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d %d " ,&n,&m); ^ user.cpp:25:28: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(mat[i],m+1,fi); ^