解决方案无法编译

Question

我正在尝试制作简单的整数练习页面和解决方案页面。

为什么这段代码不能编译？

我很确定问题出在线路上\xdef，但我不知道问题是什么。

任何帮助都将不胜感激。谢谢！

\documentclass{article}

\usepackage{ifthen}
\usepackage{pgf}
 \pgfmathsetseed{\number\pdfrandomseed}
\usepackage{pgffor}

\newcommand{\EquationSolution}{}
\newcommand{\EquationExercise}{}

\newcommand{\InitVariables}
{%
 \pgfmathrandominteger{\A}{-10}{10} % the first number
 \pgfmathrandominteger{\C}{-10}{10} % the answer
 \ifthenelse{\equal{\A}{\C}}{\InitVariables}{} 
 \pgfmathsetmacro{\B}{int(\C-\A)} % The second number

 \renewcommand{\EquationExercise}
  {%
   \ifthenelse{\B<0}
   {\Large $\A\B=\_\_\_$}
   {\Large $\A+\B=\_\_\_$}
  }

 \renewcommand{\EquationSolution}
  {%
   \ifthenelse{\B<0}
   {\Large $\A\B=\C$}
   {\Large $\A+\B=\C$}
  }
}


\newcommand{\ManySolutions}{}

\newcommand{\ManyExercises}[1]
{%
 \foreach \x in {1,...,#1}
  {%
   \InitVariables \EquationExercise
   \xdef\ManySolutions{\ManySolutions \EquationSolution} % Compiles if this line is commented out [along with the other line below]
  }
}


\setlength\parindent{0pt}
\pagestyle{empty}


\begin{document}
\section*{Exercises}
\ManyExercises{5}
\section*{Solutions}
\ManySolutions % also must be commented out to compile
\end{document}

Answer 1

首先破裂的\xdef是\ifthenelse，然后也是\Large和\_。

因为\Large它很容易：它不属于那里，而是属于围绕调用\ManyExercises和的命令的环境\ManySolutions。

对于其他部分：

\documentclass{article}

\usepackage{pgfmath}
\usepackage{pgffor}

\pgfmathsetseed{\number\pdfrandomseed}

\newcommand{\EquationSolution}{}
\newcommand{\EquationExercise}{}
\newcommand{\ManySolutions}{}
\protected\def\dummy{\makebox[2em]{\hrulefill}}

\newcommand{\InitVariables}
{%
 \pgfmathrandominteger{\A}{-10}{10} % the first number
 \pgfmathrandominteger{\C}{-10}{10} % the answer
 \ifnum\A=\C\relax\InitVariables\fi
 \pgfmathsetmacro{\B}{int(\C-\A)} % The second number

 \edef\EquationExercise
  {%
   $\A\ifnum\B<0 \else +\fi\B=\dummy$\par
  }

 \edef\EquationSolution
  {%
   $\A\ifnum\B<0 \else +\fi\B=\C$
  }
}



\newcommand{\ManyExercises}[1]
{%
 \foreach \x in {1,...,#1}
  {%
   \InitVariables \EquationExercise
   \toks0=\expandafter{\ManySolutions\par}
   \xdef\ManySolutions{\the\toks0 \unexpanded\expandafter{\EquationSolution}} % Compiles if this line is commented out [along with the other line below]
  }
}


\setlength\parindent{0pt}
\pagestyle{empty}


\begin{document}
\section*{Exercises}
{\Large\ManyExercises{5}\par}
\section*{Solutions}
{\Large\ManySolutions\par}
\end{document}