Why if loop is so slow?

I have a datasheet of 34*300000 and a 1D array of 300. Inside the array I got random numbers between 1 and 300k and I want to allocate the value of 1 into xth column of 34th row of the datasheet, a fairly simple task. I tried the below code but it take 10+ minutes to run (on 8gb RAM, corei7 6500 cpu):

    For i = 1:300
    Datasheet(34,array(i)) = 1
    End

Any suggestions on what is going wrong?

Answer 1

[Abbas Nasri]

I figured it out, a semicolon at the end of the second line did the job 🤦🏻♂

[madhan ravi]

Things happen xD