十进制ip转换为点分式ip

union IPNode
{
    unsigned int addr;
    struct
    {
        unsigned char s1;
        unsigned char s2;
        unsigned char s3;
        unsigned char s4;
    };
};

char* my_DotDec(unsigned int ip, char *buffer)
{
     union IPNode x;
    
     x.addr = ip;      
     sprintf(buffer,"%d.%d.%d.%d",x.s1,x.s2,x.s3,x.s4);
    
     return buffer;         
}