Ok, That you. | | cc | | 邮箱:caipenghui_c@163.com | 签名由 网易邮箱大师 定制 On 08/22/2018 22:32, Ralph Corderoy wrote: > I want to figure out if the book is right or the compiler is right. 5050 is the right answer. It's the 100th triangular number. https://en.wikipedia.org/wiki/Triangular_number Please let this off-topic thread die. -- Cheers, Ralph. https://plus.google.com/+RalphCorderoy