Word frequencies

Our first example illustrates associative arrays for counting. Suppose you want to count the number of times each word appears in the input, where a word is any contiguous sequence of non-blank, non-tab characters. The following program prints the word frequencies, sorted in decreasing order.

   { for (w = 1; w <= NF; w++) count[$w]++ }
   END  { for (w in count) print count[w], w | "sort -nr" }