1.3 Finding Duplicate Lines

Programs for file copying, printing, searching, sorting, counting, and the like all have a similar structure: a loop over the input, some computation on each element, and generation of output on the fly or at the end. We’ll show three variants of a program called dup; it is partly inspired by the Unix uniq command, which looks for adjacent duplicate lines. The structures and packages used are models that can be easily adapted.

The first version of dup prints each line that appears more than once in the standard input, preceded by its count. This program introduces the if statement, the map data type, and the bufio package.

// Dup1 prints the text of each line that ...

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