Since C doesn't have a "string" datatype in the standard library, working with strings can be a pain.
Luckily C has a "char" datatype, though. So the first trick is to create an array of chars. 
Let's have a look at this code:

So far we have declared an array with 5 elements and called it "c".

Then we have asked the user for input.

To take the input as a string we use "%s".

The pointer "&c" tells the compiler to store the values of the array at an adress of the RAM.

Now let's add some more code to see what happens with the user input.

The for loop iterates through each index of the array (from 0 to 4 = 5 elements) and prints each value of each index on the console like this:

As we can see the program converted the user input into ASCII values (integers).

With this knowledge we can compare each element of the array to check if the user has entered "hello" or not.

The output on the console will be like this:

I hope that this is useful for some of you.

Who knows, maybe we will see some nice text-based adventure games soon :D