继续解决我的问题问题
我有循环问题\int_do_while:nn
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
! LaTeX error: "kernel/command-already-defined"
!
! Control sequence \l_number_int already defined.
!
! See the LaTeX3 documentation for further information.
!
! For immediate help type H <return>.
!...............................................
在下面的代码中。当我手动更改时\l_element_int，定义的问题\l_number_int不会出现。
\documentclass[12pt]{article}
\usepackage{xparse}
\ExplSyntaxOn
\int_new:N \l_initial_number_int
\cs_new_protected:Npn \count_number_of_elements:Nn #1#2
{
\int_new:N \l_number_int
\int_set:Nn \l_number_int {1}
\int_set:Nn \l_initial_number_int {#2}
\int_do_while:nn
{\l_initial_number_int != 1}
{
\int_incr:N \l_number_int
\int_if_even:nTF {\l_initial_number_int}
{\int_set:Nn \l_initial_number_int {\l_initial_number_int/2} }
{\int_set:Nn \l_initial_number_int {3*\l_initial_number_int + 1} }
}
\int_set_eq:NN #1 \l_number_int
}
\NewDocumentCommand{\MaxNumber}{ m }
{
\int_new:N \l_bound_element_int
\int_set:Nn \l_bound_element_int {#1}
\int_new:N \l_element_int
\int_set:Nn \l_element_int {2}
\int_do_while:nn {\l_element_int < \l_bound_element_int}
{
\count_number_of_elements:Nn \l_tmpa_int {\int_use:N \l_element_int}
\int_incr:N \l_element_int
\int_use:N \l_element_int -- \int_use:N \l_tmpa_int\\
}
}
\ExplSyntaxOff
\begin{document}
\MaxNumber{13}
\end{document}
答案1
永远不要在函数内声明变量。声明（\..._new:N）始终是全局的，显然每个名称只能声明一次。这样你就永远不会调用函数两次。
\documentclass[12pt]{article}
\usepackage{xparse}
\ExplSyntaxOn
\int_new:N \l_initial_number_int
\int_new:N \l_number_int
\int_new:N \l_bound_element_int
\int_new:N \l_element_int
\cs_new_protected:Npn \count_number_of_elements:Nn #1#2
{
\int_set:Nn \l_number_int {1}
\int_set:Nn \l_initial_number_int {#2}
\int_do_while:nn
{\l_initial_number_int != 1}
{
\int_incr:N \l_number_int
\int_if_even:nTF {\l_initial_number_int}
{\int_set:Nn \l_initial_number_int {\l_initial_number_int/2} }
{\int_set:Nn \l_initial_number_int {3*\l_initial_number_int + 1} }
}
\int_set_eq:NN #1 \l_number_int
}
\NewDocumentCommand{\MaxNumber}{ m }
{
\int_set:Nn \l_bound_element_int {#1}
\int_set:Nn \l_element_int {2}
\int_do_while:nn {\l_element_int < \l_bound_element_int}
{
\count_number_of_elements:Nn \l_tmpa_int {\int_use:N \l_element_int}
\int_incr:N \l_element_int
\int_use:N \l_element_int -- \int_use:N \l_tmpa_int\\
}
}
\ExplSyntaxOff
\begin{document}
\MaxNumber{13}
\end{document}