According to my books the bond order of $\ce{CO+}$ is  $3.5$. But shouldn't it be $2.5$? On googling this, I found the following [answer][1] that is on Stack Exchange but its only talks about the bond length.


I am unable to understand why it is $3.5$ as I am in class 11.


  [1]: http://chemistry.stackexchange.com/q/9510/17988