在人教A版高中数学必修3第一章《算法初步》中,循环结构有下面两种形式:(1)当型循环结构,如下左图所示,它的功能是当给定的条件P成立时,执行A框,A框执行完毕后,再判断条件P是否成立,如果仍然成立,再执行A框,如此反复执行A框,直到某一次条件P不成立为止,此时不再执行A框,离开循环结构. In the first edition of the “A Preliminary Algorithm” of the 3rd chapter of the “Meaning of Teaching A”, there are the following two forms of cyclic structure: (1) When the type of cyclic structure, as shown in the left figure below, its function is when the given condition P When it is established, execute the A box, and after the execution of the A box, determine whether the condition P is established. If it is still valid, execute the A box again. This repeatedly executes the A box until a condition P is not established, and the A box is not executed at this time. , leave the circulation structure.