Keywords: lpg

Next: 8.2.4 Termcap Capabilities Up: 8.2 The Termcap Library Previous: 8.2.2 Find a Terminal

## 8.2.3 Look at a Terminal Description

Every piece of information is called a capability, every capability is a two letter code, and every two letter code is followed by the value for the capability. Possible types are:

- Numeric: For instance co - number of columns
- Boolean or Flag: For instance hc - hardcopy terminal
- String: For instance st - set tab stop

Each capability is associated with a single value type. (co is always numeric, hc is always a flag and st is always a string). There are three different types of values, so there are also three functions to interrogate them. `char *name` is the two letter code for the capability.

- `int tgetnum(char *name)`
  Get a capability value that is numeric, such as co. tgetnum(...) returns the numeric value if the capability is available, otherwise 1. (Note: the returned value is not negative.)
- `int tgetflag(char *name)`
  Get a capability value that is boolean (or flag). Returns 1 if the flag is present, 0 otherwise.
- `char *tgetstr(char *name, char **area)`
  Get a capability value that is a string. Returns a pointer to the string or NULL if not present. In the GNU version, if `area` is NULL, termcap will allocate memory by itself. Termcap will never refer to this pointer again, so don't forget to free `name` before leaving the program. This method is preferred, because you don't know how much space is needed for the pointer, so let termcap do this for you.