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9.3.1 Header Information Routines

Reserve space in the CHU for MOREKEYS more header keywords. This routine may be called to allocate space for additional keywords at the time the header is created (prior to writing any data). CFITSIO can dynamically add more space to the header when needed, however it is more efficient to preallocate the required space if the size is known in advance.

  int fits_set_hdrsize / ffhdef
      (fitsfile *fptr, int morekeys, > int *status)

Return the number of keywords in the header (not counting the END keyword) and the current position in the header. The position is the number of the keyword record that will be read next (or one greater than the position of the last keyword that was read). A value of 1 is returned if the pointer is positioned at the beginning of the header.

  int fits_get_hdrpos / ffghps
      (fitsfile *fptr, > int *keysexist, int *keynum, int *status)