这是什么情况 怎么改？？

Answer 1

把4改成i 

for(int j = 0; j<i ; j++){}

Answer 2

数组越界了

Answer 3

数组长度为3，下标是从0开始的，只有a[0]，a[1]，a[2]三个元素

Answer 4

https://www.imooc.com/wenda/detail/344144

https://www.imooc.com/wenda/detail/346207

https://www.imooc.com/wenda/detail/353317

https://www.imooc.com/wenda/detail/337893

https://www.imooc.com/wenda/detail/346942

https://www.imooc.com/wenda/detail/333816

https://www.imooc.com/wenda/detail/338781

https://www.imooc.com/wenda/detail/349596

https://www.imooc.com/wenda/detail/349622

https://www.imooc.com/wenda/detail/350034

https://www.imooc.com/wenda/detail/335786

https://www.imooc.com/wenda/detail/350633

https://www.imooc.com/wenda/detail/354500

https://www.imooc.com/wenda/detail/351688

https://www.imooc.com/wenda/detail/354827

https://www.imooc.com/wenda/detail/338424

https://www.imooc.com/wenda/detail/334286

https://www.imooc.com/wenda/detail/351642

https://www.imooc.com/wenda/detail/339687

https://www.imooc.com/wenda/detail/334873

https://www.imooc.com/wenda/detail/354101

https://www.imooc.com/wenda/detail/354206

https://www.imooc.com/wenda/detail/353905

https://www.imooc.com/wenda/detail/355670

https://www.imooc.com/wenda/detail/350975

https://www.imooc.com/wenda/detail/335901

https://www.imooc.com/wenda/detail/333764

https://www.imooc.com/wenda/detail/352383

https://www.imooc.com/wenda/detail/353360

https://www.imooc.com/wenda/detail/340667

https://www.imooc.com/wenda/detail/332828

https://www.imooc.com/wenda/detail/335570

https://www.imooc.com/wenda/detail/344803

https://www.imooc.com/wenda/detail/353205

https://www.imooc.com/wenda/detail/341156

https://www.imooc.com/wenda/detail/350135

https://www.imooc.com/wenda/detail/351412

https://www.imooc.com/wenda/detail/344029

https://www.imooc.com/wenda/detail/349138

https://www.imooc.com/wenda/detail/350658

https://www.imooc.com/wenda/detail/341855

https://www.imooc.com/wenda/detail/345400

https://www.imooc.com/wenda/detail/333241

https://www.imooc.com/wenda/detail/356053

https://www.imooc.com/wenda/detail/342011

https://www.imooc.com/wenda/detail/353872

https://www.imooc.com/wenda/detail/351534

https://www.imooc.com/wenda/detail/341846

https://www.imooc.com/wenda/detail/335057

https://www.imooc.com/wenda/detail/350000

https://www.imooc.com/wenda/detail/349488

https://www.imooc.com/wenda/detail/332317

https://www.imooc.com/wenda/detail/341618

https://www.imooc.com/wenda/detail/344328

https://www.imooc.com/wenda/detail/339163

https://www.imooc.com/wenda/detail/348506

https://www.imooc.com/wenda/detail/352105

https://www.imooc.com/wenda/detail/342332

https://www.imooc.com/wenda/detail/350321

https://www.imooc.com/wenda/detail/351445

https://www.imooc.com/wenda/detail/335294

https://www.imooc.com/wenda/detail/336721

https://www.imooc.com/wenda/detail/338205

https://www.imooc.com/wenda/detail/355978

https://www.imooc.com/wenda/detail/334250

https://www.imooc.com/wenda/detail/338686

https://www.imooc.com/wenda/detail/341720

https://www.imooc.com/wenda/detail/348715

https://www.imooc.com/wenda/detail/339915

https://www.imooc.com/wenda/detail/336230

https://www.imooc.com/wenda/detail/338953

https://www.imooc.com/wenda/detail/339533

https://www.imooc.com/wenda/detail/339428

https://www.imooc.com/wenda/detail/346692

https://www.imooc.com/wenda/detail/332130

https://www.imooc.com/wenda/detail/341331

https://www.imooc.com/wenda/detail/338346

https://www.imooc.com/wenda/detail/339281

https://www.imooc.com/wenda/detail/347257

https://www.imooc.com/wenda/detail/356058