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

typedef struct PATIENT
{
    char sex[15];
    char name[30];
    char surname[15];
    int diagnosis;
    int date[1];
} PATIENT;

int cmp(const void * a, const void * b)
{
    return strcmp(((const PATIENT*)a)->surname,((const PATIENT*)b)->surname);
}

int main()
{
    PATIENT massive[5] = {{"","abc","def"},{"","xzy","vcd"},{"","hfk","hdb"},{"","ghd","vqw"},{"","ffg","ijk"}};

    for(int i = 0; i < 5; ++i) printf("%s\t",massive[i].surname); puts("");

    qsort(massive,5,sizeof(PATIENT),cmp);

    for(int i = 0; i < 5; ++i) printf("%s\t",massive[i].surname); puts("");
}