求教高手

#include <stdio.h>
#include <string.h>
#define SIZE 5
struct ip_net
{
    char IP[SIZE];
    char NET[SIZE];
}network[5]={
    {"du",54},
    {"du",67},
    {"wang",87},
    {"wang",56},
    {"we",90}
    };
void main()
{
    int i,j,index;
    index=16;
    for(i=0;i<5;i++)
    {
        for(j=0;j!=i,j<5;j++)
        {
            if(strcmp(network[i].IP,network[j].IP)==0)
                index--;
        }
    
    }        
    printf("%d\n",index);
    
}


如何计算不同的名字个数？？
----------------解决方案--------------------------------------------------------
先按名字排序````在统计
----------------解决方案--------------------------------------------------------