title: R function with a dynamic URL
body: <p>Please help R novice with an assignment!
  I need to write a function, taking a single argument year, which reads data from csv files from the website. These csv files are available at the addresses like the one below where only the year part changes: 'https://www.nbp.pl/kursy/Archiwum/archiwum_tab_a_2020.csv'</p>
  <p>I’m trying to separate URL into parts and then paste() them together, including the year input from the function. My code is below. But it causes the following error:
  Error in urlPart1 + urlYear : non-numeric argument to binary operator</p>
  <p>How can I overcome this error or could you advise me any other approach, maybe some regular expressions? Also I’m afraid we are not allowed to use different fancy packages.</p>
  <pre><code>my_func &lt;- function(year) {
    urlPart1 = 'https://www.nbp.pl/kursy/Archiwum/archiwum_tab_a_'
    urlYear = year
    urlPart2 = '.csv'
    url = paste(urlPart1, urlYear, urlPart2, sep = “”)
    d = read.table(url, header = TRUE, sep = ';', fill = TRUE)
  }
  print(my_func(2018))
  </code></pre>