函数是一组一起执行一个任务的语句。每个 C++ 程序都至少有一个函数，即主函数 main() ，所有简单的程序都可以定义其他额外的函数。(A function is a set of statements that perform tasks together. Every C++ program has at least one function, that is, the main function main (). All the simple programs can define ot