can you explain what does it mean?

```
 argc >= 3 ? atoi(argv[2]) : 40;

```

And second question : does exist libarries of function - parameters which is necessary, structure something like this

```
 CVAPI(void)  cvAddS( const CvArr* src, CvScalar value, CvArr* dst,
                 const CvArr* mask CV_DEFAULT(NULL));

```