remix-project/docs/udapp.md

Run & Deploy (part 2)
=====================

## Deployed contracts

This section in the Run tab contains a list of deployed contracts to interact with through autogenerated UI of the deployed contract (also called udapp).

The deployed contract appears but is in its collapsed form.

![](images/a-debug2-udapp1a.png)

Click the sideways caret to open it up.

![](images/a-debug3-udapp2.png)

You will see the functions in the contract.  The functions buttons can have different color buttons.

-   Functions that are `constant` or `pure` functions in Solidity have a blue buttons. Clicking one of this type does not create a new transaction. So clicking will not cause state changes - it will only return a value stored in the contract - so it won't cost you anything in gas fees.

-   Functions that change the state of the contract AND that do not accept Ether are called `non-payable` functions and have an orange button. Clicking on them will create a transaction and thus cost gas.

-   Functions that have red buttons are `payable` functions in Solidity. Clicking one of these will create a new transaction and this transaction can accept a **value**.  The **value** is put in in the Value field which is under the Gas Limit field.

![](images/a-jvm-calling-instance.png)


For more information see more about [Solidity
modifier](http://solidity.readthedocs.io/en/develop/miscellaneous.html?highlight=pure#modifiers)
.

If a function requires input parameters, well.. you gotta put them in.

## Inputting parameters

![](images/a-udapp-inputs.png)

### Inputting parameters in the collapsed view

(Inputting all the parameters in a single input box)
+ The input box tells you what type each parameter needs to be.
+ Numbers and addresses do not need to be wrapped in double quotes.  
+ Strings need to be wrapped.
+ Parameters are separated by commas.

In the example above the "delegate" function has 3 parameters.

### Inputting parameters in the expanded view
Clicking the 'down' caret brings you to the *Multi-param Manager* - where you can input the parameters one at a time. **Much less confusing!**

![](images/a-udapp-multi-param-man.png)

In the expanded view, strings do not need to be wrapped.  

Clicking the clipboard icon will encode the inputs and will copy them.  Only a valid set of inputs can be encoded.  

So if you made a mistake and put a uint8 where an address should have been, clicking the clipboard here will give you an error.

### Passing in a tuple or a struct to a function
To pass a tuple in, you need to put in an an array [].

Similarly, to pass in a struct as a parameter of a function, it needs to be put in as an array [].  Also note that the line
`pragma experimental ABIEncoderV2;`
needs to put in at the top of the solidity file.