Question: What I have:

```
char cmd[50] = "some text here";
char v[] = {'a','s','d','c','b'};

```

So I want to concatenate `cmd` by adding a letter from `v`.

Obviously: 

```
strcat(cmd, v[3]);

```

doesn't work because `strcat` doesn't accept the `v[n]` parameter `n = int`.

Answer: 
Do ***not*** use this:

```
strcat(cmd,&v[3]);

```

`&v[3]` is not a pointer to a null terminated string! instead use 

```
strncat(cmd, &v[3], 1);

```
First, make sure the variable 'cmd' has enough memory allocated.

Second, the mention to 'v[3]' is the value which is a signed byte. You have to use the following call to strncat (not strcat):

```
strncat(cmd,&v[3],1);

```