3.1. igraph_error_type_t — Error code type.

3.1. `igraph_error_type_t` — Error code type.

typedef enum {
  IGRAPH_SUCCESS       = 0,
  IGRAPH_FAILURE       = 1,
  IGRAPH_ENOMEM        = 2,
  IGRAPH_PARSEERROR    = 3,
  IGRAPH_EINVAL        = 4,
  IGRAPH_EXISTS        = 5,
  IGRAPH_EINVEVECTOR   = 6,
  IGRAPH_EINVVID       = 7,
  IGRAPH_NONSQUARE     = 8,
  IGRAPH_EINVMODE      = 9,
  IGRAPH_EFILE         = 10,
  IGRAPH_UNIMPLEMENTED = 12,
  IGRAPH_INTERRUPTED   = 13,
  IGRAPH_DIVERGED      = 14,
  IGRAPH_ARPACK_PROD      = 15,
  IGRAPH_ARPACK_NPOS      = 16,
  IGRAPH_ARPACK_NEVNPOS   = 17,
  IGRAPH_ARPACK_NCVSMALL  = 18,
  IGRAPH_ARPACK_NONPOSI   = 19,
  IGRAPH_ARPACK_WHICHINV  = 20,
  IGRAPH_ARPACK_BMATINV   = 21,
  IGRAPH_ARPACK_WORKLSMALL= 22,
  IGRAPH_ARPACK_TRIDERR   = 23,
  IGRAPH_ARPACK_ZEROSTART = 24,
  IGRAPH_ARPACK_MODEINV   = 25,
  IGRAPH_ARPACK_MODEBMAT  = 26,
  IGRAPH_ARPACK_ISHIFT    = 27,
  IGRAPH_ARPACK_NEVBE     = 28,
  IGRAPH_ARPACK_NOFACT    = 29,
  IGRAPH_ARPACK_FAILED    = 30,
  IGRAPH_ARPACK_HOWMNY    = 31,
  IGRAPH_ARPACK_HOWMNYS   = 32,
  IGRAPH_ARPACK_EVDIFF    = 33,
  IGRAPH_ARPACK_SHUR      = 34,
  IGRAPH_ARPACK_LAPACK    = 35,
  IGRAPH_ARPACK_UNKNOWN   = 36,
  IGRAPH_ENEGLOOP         = 37
} igraph_error_type_t;

These are the possible valued returned by igraph functions. Note that these are interesting only if you defined an error handler with igraph_set_error_handler(). Otherwise the program is aborted and the function causing the error never returns.

Values:

`IGRAPH_SUCCESS`:	The function successfully completed its task.
`IGRAPH_FAILURE`:	Something went wrong. You'll almost never meet this error as normally more specific error codes are used.
`IGRAPH_ENOMEM`:	There wasn't enough memory to allocate on the heap.
`IGRAPH_PARSEERROR`:	A parse error was found in a file.
`IGRAPH_EINVAL`:	A parameter's value is invalid. Eg. negative number was specified as the number of vertices.
`IGRAPH_EXISTS`:	A graph/vertex/edge attribute is already installed with the given name.
`IGRAPH_EINVEVECTOR`:	Invalid vector of vertex ids. A vertex id is either negative or bigger than the number of vertices minus one.
`IGRAPH_EINVVID`:	Invalid vertex id, negative or too big.
`IGRAPH_NONSQUARE`:	A non-square matrix was received while a square matrix was expected.
`IGRAPH_EINVMODE`:	Invalid mode parameter.
`IGRAPH_EFILE`:	A file operation failed. Eg. a file doesn't exist, or the user ha no rights to open it.
`IGRAPH_UNIMPLEMENTED`:	Attempted to call an unimplemented or disabled (at compile-time) function.
`IGRAPH_DIVERGED`:	A numeric algorithm failed to converge.
`IGRAPH_ARPACK_PROD`:	Matrix-vector product failed.
`IGRAPH_ARPACK_NPOS`:	N must be positive.
`IGRAPH_ARPACK_NEVNPOS`:	NEV must be positive.
`IGRAPH_ARPACK_NCVSMALL`:	NCV must be bigger.
`IGRAPH_ARPACK_NONPOSI`:	Maximum number of iterations should be positive.
`IGRAPH_ARPACK_WHICHINV`:	Invalid WHICH parameter.
`IGRAPH_ARPACK_BMATINV`:	Invalid BMAT parameter.
`IGRAPH_ARPACK_WORKLSMALL`:	WORKL is too small.
`IGRAPH_ARPACK_TRIDERR`:	LAPACK error in tridiagonal eigenvalue calculation.
`IGRAPH_ARPACK_ZEROSTART`:	Starting vector is zero.
`IGRAPH_ARPACK_MODEINV`:	MODE is invalid.
`IGRAPH_ARPACK_MODEBMAT`:	MODE and BMAT are not compatible.
`IGRAPH_ARPACK_ISHIFT`:	ISHIFT must be 0 or 1.
`IGRAPH_ARPACK_NEVBE`:	NEV and WHICH='BE' are incompatible.
`IGRAPH_ARPACK_NOFACT`:	Could not build an Arnoldi factorization.
`IGRAPH_ARPACK_FAILED`:	No eigenvalues to sufficient accuracy.
`IGRAPH_ARPACK_HOWMNY`:	HOWMNY is invalid.
`IGRAPH_ARPACK_HOWMNYS`:	HOWMNY='S' is not implemented.
`IGRAPH_ARPACK_EVDIFF`:	Different number of converged Ritz values.
`IGRAPH_ARPACK_SHUR`:	Error from calculation of a real Schur form.
`IGRAPH_ARPACK_LAPACK`:	LAPACK (dtrevc) error for calculating eigenvectors.
`IGRAPH_ARPACK_UNKNOWN`:	Unkown ARPACK error.
`IGRAPH_ENEGLOOP`:	Negative loop detected while calculating shortest paths.