$ perl -e 'my ($v1, $v2) = qw{A B}; printf "_%s_%s_\n", $v1, $v2'
_A_B_

##</code><code>##

$ perl -le 'my ($v1, $v2) = qw{A B}; print join "_", "", $v1, $v2, ""'
_A_B_

##</code><code>##

$ perl -le 'my @x = "A" .. "Z"; print join "_", "", @x, ""'
_A_B_C_D_E_F_G_H_I_J_K_L_M_N_O_P_Q_R_S_T_U_V_W_X_Y_Z_