If you’re looking for a way to show discounted price on product page of WooCommerce, then this is just the thing.
Using the below codes will show the discounted price on product page if a customer uses a coupon.
Just paste this php code in your functions.php

cart->has_discount() ) {
		$values = array (
			'data'		=> $product,
			'quantity'	=> 1
		);
		$coupons = WC()->cart->get_coupons();
		$_price = $product->get_price();
		$undiscounted_price = $_price;
		if ( ! empty( $coupons ) ) {
			foreach ( $coupons as $code => $coupon ) {
				if ( $coupon->is_valid() && ( $coupon->is_valid_for_product( $product, $values ) || $coupon->is_valid_for_cart() ) ) {
					$discount_amount = $coupon->get_discount_amount( 'yes' === get_option( 'woocommerce_calc_discounts_sequentially', 'no' ) ? $_price : $undiscounted_price, $values, true );
					$discount_amount = min( $_price, $discount_amount );
					$_price          = max( $_price - $discount_amount, 0 );
				}
				if ( 0 >= $_price ) {
					break;
				}
			}
			if ( ( $product->get_price() > 0 ) && ( $undiscounted_price !== $_price ) )
				$price = wc_format_sale_price( wc_get_price_to_display( $product, array( 'price' => $undiscounted_price ) ), $_price ) . $product->get_price_suffix();
		}
	}
	return $price;
}

Above code works with WooCommerce 3.x. If your using lower versions, below code works for WooCommerce 2.6.x

cart->has_discount() ) {
		$values = array (
			'data'		=> $product,
			'quantity'	=> 1
		);
		$coupons = WC()->cart->get_coupons();
		$_price = $product->get_price();
		$undiscounted_price = $_price;
		if ( ! empty( $coupons ) ) {
			foreach ( $coupons as $code => $coupon ) {
				if ( $coupon->is_valid() && ( $coupon->is_valid_for_product( $product, $values ) || $coupon->is_valid_for_cart() ) ) {
					$discount_amount = $coupon->get_discount_amount( 'yes' === get_option( 'woocommerce_calc_discounts_sequentially', 'no' ) ? $_price : $undiscounted_price, $values, true );
					$discount_amount = min( $_price, $discount_amount );
					$_price          = max( $_price - $discount_amount, 0 );
				}
				if ( 0 >= $_price ) {
					break;
				}
			}
			$display_price         = $product->get_display_price( $_price );
			$display_regular_price = $product->get_display_price( $product->get_regular_price() );
			if ( ( $product->get_price() > 0 ) && ( $display_regular_price !== $display_price ) ) {
				$price = $product->get_price_html_from_to( $display_regular_price, $display_price ) . $product->get_price_suffix();
			}
		}
	}
	return $price;
}