Returns the error message corresponding to the last error triggered by a library function.

The following shows how this function might be used in error-checking:

p.solve()
print("Current error status:", p.getlasterror())

x = xpress.var()
try:
    p.addVariable(x)
    p.addVariable(x)
except RuntimeError as e:
    print(e)

try:
    p.addVariable('John Cleese')
except RuntimeError as e:
    print(e)

The problem.getlasterror() function is an API wrapper for the XPRSgetlasterror() function in the Xpress C API. For this reason, errors that occur within the Xpress API are reported by getlasterror(). Errors that occur at the level of the Python interface are not reported by getlasterror. Both classes of errors can be handled with a try/ except construct. In the two examples below, the first is an error that is detected by the Xpress API and propagated to a Python error, while the second is an incorrect statement for the Python module. They both trigger a RuntimeError exception.

problem.addcbmessage, problem.setlogfile.