TAN — TRAP RAISE

Contents

• TAN — Tangent
• TESTEVENT — Tests if an event has occurred
• TRAP — Traps errors
• TRAP RAISE — Clears the trap flag

TAN — Tangent

Usage:      t=TAN(angle)

Returns the tangent of angle, an angle expressed in radians.

To convert from radians to degrees, use the DEG function.

TESTEVENT — Tests if an event has occurred

Usage:      t%=TESTEVENT

Returns ‘True’ if an event has occurred, otherwise returns ‘False’. The event is not read by TESTEVENT - it may be read with GETEVENT, GETEVENT32, or GETEVENTA32.

Warning: it is recommended that you use either GETEVENT32 or GETEVENTA32 without TESTEVENT as TESTEVENT may use a lot of power, especially when used in a loop as will often be the case.

TRAP — Traps errors

Section Contents

• Trapping data file commands
• Trapping file commands
• Trapping directory commands
• Trapping data entry commands
• Trapping graphics commands

Usage: TRAP command

TRAP is an error handling command. It may precede any of these commands:

Trapping data file commands

APPEND, UPDATE, BACK, NEXT, LAST, FIRST, POSITION, USE, CREATE, OPEN, OPENR, CLOSE, DELETE, MODIFY, INSERT, PUT, CANCEL

Trapping file commands

COPY, ERASE, RENAME, LOPEN, LCLOSE, LOADM, UNLOADM

Trapping directory commands

MKDIR, RMDIR

Trapping data entry commands

EDIT, INPUT

Trapping graphics commands

gSAVEBIT, gCLOSE, gUSE, gUNLOADFONT, gFONT, gPATT, gCOPY

For example, TRAP FIRST.

Any error resulting from the execution of the command will be trapped. Program execution will continue at the statement after the TRAP statement, but ERR will be set to the error code.

TRAP overrides any ONERR.

TRAP RAISE — Clears the trap flag

Usage:      TRAP RAISE x%

Sets the value of ERR to x% and clears the trap flag.

For a full explanation of the use of RAISE, see Runtime errors — Handling errors reported while running programs.