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: http://www.stsci.edu/~sontag/spicedocs/cspice/ekrcec_c.html
Дата изменения: Sat Dec 17 06:08:56 2005 Дата индексирования: Mon Apr 11 00:01:04 2016 Кодировка: Поисковые слова: annular solar eclipse |
Read data from a character column in a specified EK record.
EK
Variable I/O Description -------- --- -------------------------------------------------- handle I Handle attached to EK file. segno I Index of segment containing record. recno I Record from which data is to be read. column I Column name. lenout I Maximum length of output strings. nvals O Number of values in column entry. cvals O Character values in column entry. isnull O Flag indicating whether column entry is null.
handle is an EK file handle. The file may be open for read or write access. segno is the index of the segment from which data is to be read. The first segment in the file has index 0. recno is the index of the record from which data is to be read. This record number is relative to the start of the segment indicated by segno; the first record in the segment has index 0. column is the name of the column from which data is to be read. lenout is the maximum string length that can be accommodated in the output array cvals. This length must large enough to hold the longest element of the specified column entry, including a null terminator. If the column element contains strings of length up to n characters, lenout should be set to n + 1.
nvals, cvals are, respectively, the number of values found in the specified column entry and the set of values themselves. The array cvals must have sufficient string length to accommodate the longest string in the returned column entry. The calling application should declare cvals with dimension [nelts][lenout] where nelts is the maximum number of elements that occur in any entry of the specified column. For columns having fixed-size entries, when a a column entry is null, nvals is still set to the column entry size. For columns having variable- size entries, nvals is set to 1 for null entries. isnull is a logical flag indicating whether the returned column entry is null.
None.
This routine is a utility that allows an EK file to be read directly without using the high-level query interface.
1) Read the value in the third record of the column ccol in the fifth segment of an EK file designated by handle. #include "SpiceUsr.h" . . . ekrcec_c ( handle, 4, 2, "CCOL", lenout, &nvals, &cval, &isnull );
1) EK files open for write access are not necessarily readable. In particular, a column entry can be read only if it has been initialized. The caller is responsible for determining when it is safe to read from files open for write access.
1) If handle is invalid, the error will be diagnosed by routines called by this routine. 2) If segno is out of range, the error will diagnosed by routines called by this routine. 3) If recno is out of range, the error will diagnosed by routines called by this routine. 4) If column is not the name of a declared column, the error will be diagnosed by routines called by this routine. 5) If column specifies a column of whose data type is not character, the error SPICE(WRONGDATATYPE) will be signaled. 6) If column specifies a column of whose class is not a character class known to this routine, the error SPICE(NOCLASS) will be signaled. 7) If an attempt is made to read an uninitialized column entry, the error will be diagnosed by routines called by this routine. A null entry is considered to be initialized, but entries do not contain null values by default. 8) If an I/O error occurs while reading or writing the indicated file, the error will be diagnosed by routines called by this routine. 9) If any element of the column entry would be truncated when assigned to an element of cvals, the error will be diagnosed by routines called by this routine. 10) If the input column name string pointer is null, the error SPICE(NULLPOINTER) will be signaled. 11) If the input column name string has length zero, the error SPICE(EMPTYSTRING) will be signaled. 12) If the output string pointer cvals is null, the error SPICE(NULLPOINTER) will be signaled. 13) If the output string length indicated by lenout is less than two characters, it is too short to contain one character of output data plus a null terminator, so it cannot be passed to the underlying Fortran routine. In this event, the the error SPICE(STRINGTOOSHORT) is signaled.
See the EK Required Reading for a discussion of the EK file format.
N.J. Bachman (JPL)
None.
-CSPICE Version 1.1.0, 21-MAY-2001 (WLT) Added a cast to (char *) in the call to F2C_ConvertStrArr to support compilation under C++. -CSPICE Version 1.0.0, 04-JUL-2000 (NJB)
read character data from EK column