How to create a cross-platform smartphone application?

I am new to smartphone application Development, I have worked with .NET web and Windows Forms applications and only used the C# language.

I am planning to make a simple application which can run on all mobile OSes, like BlackBerry, Windows Mobile, Android phones, iPhone, etc. On searching I found that all have different OSes and uses different languages. I can use the C# language and .NET since I am aware about it. After some thinking, is it possible to make a web-based application using normal website coding but make it work like开发者_开发知识库 an application?

Please suggest some method to make a application which is possible to run on all smartphones. What technology or tools can be used for developing it?

The best approach to create truly cross platform app is to use HTML5 and JavaScript. All the other options will be painful. However, of course you can't access all the features with these web applications.

One interesting framework for creating HTML5/JavaScript based apps is PhoneGap (http://www.phonegap.com/). It has quite many API's available and wide support for different platforms. (Note that browser performance varies between devices so make sure not to add too much effects and glitter)

For native apps, there's no that many frameworks but one interesting is MoSync (http://www.mosync.com/)

There can be multiple approaches to create a Cross Smatphone plateform apllication.

If you want to code just once and want to to run on multiple enviroments without any change you must go for some javascript/HTML5 bassed solutions. One that I work with is NGCore. It is a development framework that allows games to be authored in JavaScript but with native application performance by leveraging ngmoco's ngCore libraries.

Other approach that will best suit your needs is to go for a Environment like MonoTouch. Its C# based and AFAIK you can use most of the .net API in MonoDevelope. It lets you reuse most of your code on another environment.