As they say make it work and then make it fast. Fair warning, mawk will give you tough competition on speed. Gawk should be possible to beat, its implementation

As they say make it work and then make it fast. Fair warning, mawk will give you tough competition on speed. Gawk should be possible to beat, its implementation is not very performance focused. Regarding concat, printf and sprintf would indeed work in some situations. Its not flexible enough in the following scenario: Consider an array of substrings, possibly generated by 'split'. I modify and delete some of them. Then I want to put them back together. Since i do not know ahead of time how many substrings will survive, sprintf is difficult to use.