Example of a Transformation Routine

This example is a transformation program that lets upper and lower case alphabetic characters collate together. Using this transformation, the set of keys "du Pont," "Friendly," "le Blanc," and "Madrid" collates as:

  1. du Pont

  2. Friendly

  3. le Blanc

  4. Madrid

This is in contrast to the standard M collation that orders them as:

  1. Friendly

  2. Madrid

  3. du Pont

  4. le Blanc

Example:

	#include <descrip.h>
	#include <ssdef.h>
	#define MYAPP$_SUBSC2LONG 12345678 /* Must conform to VMS error message standard */
	static unsigned char xform_table[256] =
	{
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
	16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
	32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
	48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
	64, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93,
	95, 97, 99,101,103,105,107,109,111,113,115,117,118,119,120,121,
	122, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94,
	96, 98,100,102,104,106,108,110,112,114,116,123,124,125,126,127,
	128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
	144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
	160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,
	176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
	192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
	208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
	224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
	240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255
	};
	long gtm_ac_xform(in, level, out, outlen)
	struct dsc$descriptor *in; /* the input string */
	int level; /* the subscript level */ 
	struct dsc$descriptor *out; /* the output buffer */
	int *outlen; /* the length of the output string */
	{
	int n;unsigned char *cp, *cout; /* Ensure space in the output buffer for the string. */n = in->dsc$w_length;if (n > out->dsc$w_length)return MYAPP$_SUBSC2LONG;/* There is space, copy the string, transforming, if necessary */cp = in->dsc$a_pointer; /* Address of first byte of  input string */cout = out->dsc$a_pointer; /* Address of first byte of  output buffer */while (n-- > 0)*cout++ = xform_table[*cp++];*outlen = in->dsc$w_length;return SS$_NORMAL;
	}