The memoir class - The UK TeX Archive

18.8. Changing counters18.8 CHANGING COUNTERSThis is effectively a bundling of the chngcntr package [Wil01e].\newcounter{〈ctr〉}[〈within〉]\thectrIn LaTeX a new counter called, say ctr, is created by the \newcounter command as\newcounter{ctr}. If the optional 〈within〉 argument is given, the counter ctr is resetto zero each time the counter called within is changed; the within counter must existbefore it is used as the optional argument. The command \thectr typesets the value ofthe counter ctr. This is automatically defined for you by the \newcounter command totypeset arabic numerals.\counterwithin{〈ctr〉}{〈within〉}\counterwithin*{〈ctr〉}{〈within〉}The \counterwithin macro makes a 〈ctr〉 that has been initially defined by\newcounter{ctr} act as though it had been defined by \newcounter{ctr}[within].It also redefines the \thectr command to be \thewithin.\arabic{ctr}. The starredversion of the command does nothing to the original definition of \thectr.\counterwithout{〈ctr〉}{〈within〉}\counterwithout*{〈ctr〉}{〈within〉}The \counterwithout macro makes the ctr counter that has been initially defined by\newcounter{ctr}[within] act as though it had been defined by \newcounter{ctr}.It also redefines the \thectr command to be \arabic{ctr}. The starred version of thecommand does nothing to the original definition of \thectr.Any number of \counterwithin{ctr}{...} and \counterwithout{ctr}{...}commands can be issued for a given counter ctr if you wish to toggle between the twostyles. The current value of ctr is unaffected by these commands. If you want to changethe value use \setcounter, and to change the typesetting style use \renewcommand on\thectr.\letcountercounter{〈counterA〉}{〈counterB〉}\unletcounter{〈counterA〉}At times it is handy to ‘let’ one counter act as if it was a different counter. Say you havetwo constructions, each with their own counter A and B, now you want them to cooperate,counting in unison. This can be done using the \letcountercounter.\letcountercounter{〈counterA〉}{〈counterB〉} \lets (make the same) 〈counterA〉 to〈counterB〉. The original of 〈counterA〉 is kept, such that you can unlet it later.\unletcounter{〈counterA〉} restores 〈counterA〉 to its un\let condition.This feature can be quite handy. Say for instance you want figures and tables to counterwithin the same counter (say table), then we need each change to the figure counter toactually act on the table counter. \letcountercounter{figure}{table} solves theproblem.327