help in filling the gaps..

[transgalactic2]

i cant figure out what to write instead of ??2?? ...??5??

the function rotates to the right the letters on the odd places
"num" times
if num=3 then
abcdef>>afcbed>>adcfeb>>abcdef

i solved the first one
i need hints regarding the others??

void rotateodd(char *str,int num){
    int len,last,i,j;
    char ch;
    len=strlen(str);
    if(len<4) return;
     num=??2??;
     if (num<0) num+=len/2;
    if (len%2)
          last=??3??;
   else
        last=??4??;
   for(i=0;i<num;i++){
      ch=str[last];
       for(j=last;j>1;??5??)
              ??6??=??7??;
        ??8??=ch;
   }
}

[nonoob]

See also
rotating a string question..

[itCbitC]

i can figure out what to write instead of ??2?? ...??5??

What with the question marks, are they placeholders?

[transgalactic2]

yes
instead ??2?? i need to write some thing