soundex.c

#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>

#include "soundex.h"

//--------------------------------------------------------
// FUNCTION soundex
//--------------------------------------------------------
void soundex(char *name, char *s)
{
    int si = 1;
    char c;

    //                 ABCDEFGHIJKLMNOPQRSTUVWXYZ
    char mappings[] = "01230120022455012623010202";

    s[0] = toupper(name[0]);

    for (int i = 1, l = strlen(name); i < l; i++)
    {
        c = toupper(name[i]) - 65;

        if (c >= 0 && c <= 25)
        {
            if (mappings[c] != '0')
            {
                if (mappings[c] != s[si - 1])
                {
                    s[si] = mappings[c];
                    si++;
                }

                if (si > 3)
                {
                    break;
                }
            }
        }
    }

    if (si <= 3)
    {
        while (si <= 3)
        {
            s[si] = '0';
            si++;
        }
    }
}