Compilare: user.c: In function ‘main’: user.c:18:39: warning: operation on ‘l’ may be undefined [-Wsequence-point] fprintf(fo,"%d %d\n",l+++1,l+2); ~^~ user.c:21:42: warning: operation on ‘l’ may be undefined [-Wsequence-point] fprintf(fo,"%d %d %d\n",l++,l+1,l+2); ~^~ user.c:21:42: warning: operation on ‘l’ may be undefined [-Wsequence-point] user.c:9:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d %d",&n,&m); ^~~~~~~~~~~~~~~~~~~~~~~~ user.c:12:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d",&x); ^~~~~~~~~~~~~~~~~~