I am new to openwrt.
I am trying to cross compile helloworld program.Steps are discussed below.

1] Downloaded lede SDK.
2] The SDK build successfully(using make command).
3] Then i created helloworld folder inside package folder.
4] In helloworld folder i created src folder and Makefile
5] Inside src folder contains the helloworld.cpp and its Makefile

The Makefile inside helloworld folder(in step 4) is given below :

include $(TOPDIR)/rules.mk

# Your program's name, package version and release number
PKG_NAME:=myproject
PKG_VERSION:=0.0.1
PKG_RELEASE:=1

# Setting the standard path where to build it.
# Nothing to change here actually.
PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)
include $(INCLUDE_DIR)/package.mk

# Package description
define Package/helloworld
    # Section and category in OpenWRT's package hierarchy
    SECTION:=base
    CATEGORY:=Utilities
    # Should it be built by default?
    DEFAULT:=n
    # Package title
    TITLE:=This is my first project
    # Package URL
    URL:=Other 
    # packages your program needs (our doesn't need anything, so let's comment it out)
    # DEPENDS:=+libstdcpp
endef

# Long description, you can put a few lines of text here
define Package/helloworld/description
    This! Is! My! First! Project!
endef

# What OpenWRT SDK should do before compiling the package
# 1. Create building directory
# 2. Copy package sources to it (in our case - from the src/ directory)
define Build/Prepare
    mkdir -p $(PKG_BUILD_DIR)
    $(CP) ./src/* $(PKG_BUILD_DIR)/
endef

# Building the package, nothing actually to change here now
define Build/Configure
    $(call Build/Configure/Default,--with-linux-headers=$(LINUX_DIR))
endef

# Package installation
# 1. Specify the destination directory (on Unwired One, not your PC; will be created if doesn't exists yet)
# 2. Copy executable files to it
# If you have more than one executable in you program - list them one by one
define Package/helloworld/install
    $(INSTALL_DIR) $(1)/usr/bin
    $(INSTALL_BIN) $(PKG_BUILD_DIR)/helloworld $(1)/usr/bin/
endef

$(eval $(call BuildPackage, helloworld)


6] Then from root folder i executed the make command make packages/helloworld/{clean,compile} V=s

    But I got the following error “No rule to make target ‘packages/helloworld’.
    How can i solve this issue.I need to create a package file (.ipk) of helloworld.