1：qsort函数， return *( int *)b > *(int *)a ? 1 : -1 和 return (( int *)b)[0] > ((int *)a)[0] ? 1 : -1的区别？

2：对加减乘除计算结果有什么影响？哪个正确？

  

[此贴子已经被作者于2017-2-28 15:50编辑过]

经过试验：

qsort函数， return *( int *)b > *(int *)a ? 1 : -1 ；

排序后，计算正确；

可是，在计算过程中，会出现两种不同的计算结果；只能人工计算判断哪个方法正确了！

例如：


计算结果1               计算结果2
0.855263                1
0.873563                0.837037
0.747126                0.837037
0.955556                1
0.697248                1
0.855263                1
0.747126                1
1                        0.727434
0.873563                1
0.697248                1
               
3.457421                0.997528
1.113855                0.985623
1.188587                0.981072
1.259307                0.973349
1.078908                0.978193
3.137956                0.987309
1.517089                0.993468
2.385143                0.928318
-0.240351                0.973349
1.30704                    0.978193
               
Press any key to continue                Press any key to continue

1：如果一样，那么省心不用二选一了；
2：用两个方法分别计算，计算结果不一样；
例如：

方法一：                          方法二：
3.000000  3.000000                        3.000000  3.560000        
                                
0.836066                        0.379747        
0.973958                        0.078947        
0.566474                        0.36611        
0.952919                        0.203273        
0.732824                        0.883402        
0.810247                        0.474474        
0.475907                        0.139676        
0.688853                        0.488304        
1                                0.353742        
0.863686                        0.860957        
                                
4.000000  4.000000(错误！）                        4.000000  2.000000    （正确！）   
                                
0.133929                        0.342857        
0.607143                        0.178571        
0.421053                        0.106667        
0.0058                            0.4        
1                                0.725        
1                                0.833333        
0.1875                            0.256684        
0.003                            0.4        
1                                0.296296        
1                                0.652174        
                                
7.000000  7.000000                        7.000000  3.465753        
                                
0.98926                            2.530189        
0.992717                        1.553683        
0.956527                        1.058629        
0.935797                        1.445122        
0.984023                        1.00839        
0.997038                        20.298866        
0.982813                        3.207247        
0.948814                        2.241864        
0.959189                        -0.202519        
0.984023                        1.009544        
                                
3.250000  3.250000                        3.250000  3.500000        
                                
0.832117                        0.811487        
0.809524                        0.322597        
0.835592                        0.253333        
0.944828                        0.767442        
0.845478                        0.904401        
1                                0.811487        
0.850556                        0.724638        
0.645443                        0.668966        
0.824746                        0.175758        
0.880597                        0.585284        
                                
Press any key to continue                        Press any key to continue        
                                

[此贴子已经被作者于2017-2-28 17:49编辑过]