Sort Huge amount of data using C Programming Language

//Example 1: To generate a quicksort routine which sorts an integer array
 //in increasing order, use the following lines:
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    #define GENSORT_NAME                 intquicksort
    #define GENSORT_TYPE                 int
    #define GENSORT_KEYTYPE              int
    #define GENSORT_GETKEY(a)            a
    #define GENSORT_COMPAREKEYS(k1,k2)   k1 < k2

    #include "gensort.h"

//Example 2: To generate a pointer quicksort routine that sorts a structure
//according to a string in the key field (<string.h> is included to get
//the prototype for the strcmp function):
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    #include <string.h>

    struct Test {
      char *KeyString;
      int   OtherFields;
       ....
    };

    #define GENSORT_NAME                 namequicksort
    #define GENSORT_TYPE                 struct Test
    #define GENSORT_KEYTYPE              char *
    #define GENSORT_GETKEY(a)            a.KeyString
    #define GENSORT_COMPAREKEYS(k1,k2)   strcmp(k1,k2) < 0

    #define GENSORT_USEPOINTERS

    #include "gensort.h"