来，我们看看普通的加法，对不同数据类型的执行效率

newer

1. (XD::Benchmark
   
2.   '((1+ 1)
   
3.     (+ 1 1)
   
4.     (+ 1 1.0)
   
5.     (+ 1.0 1.0)
   
6.    )
   
7. )
   
8. 
   

(XD::Benchmark<br />   '((1+ 1)<br />     (+ 1 1)<br />     (+ 1 1.0)<br />     (+ 1.0 1.0)<br />    )<br /> )<br /> <br />

1. 
   
2. Elapsed milliseconds / relative speed for 32768 iteration(s):
   
3. 
   
4.     (1+ 1)..........1313 / 1.17 <fastest>
   
5.     (+ 1 1).........1485 / 1.03
   
6.     (+ 1 1.0).......1485 / 1.03
   
7.     (+ 1.0 1.0).....1531 / 1 <slowest>
   
8. 
   

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1、整数相加， 1+函数 比 + 快
2、整数和实数相加，效率基本相同
3、实数相加，效率最慢

newer

所以，选择集操作，尽量用1+

1. (setq ss (ssget "x"))
   
2. (defun ss1 (ss / i lst e)
   
3.   (setq i -1)
   
4.   (while (setq e (ssname ss (setq i (1+ i))))
   
5.     (setq lst (cons e lst))
   
6.   )
   
7.   (princ)
   
8. )
   
9. (defun ss2 (ss / i lst e)
   
10.   (setq i -1)
    
11.   (while (setq e (ssname ss (setq i (+ i 1))))
    
12.     (setq lst (cons e lst))
    
13.   )
    
14.   (princ)
    
15. )
    
16. (defun c:tt ()
    
17.   (XD::Benchmark
    
18.     '((ss1 ss)
    
19.       (ss2 ss)
    
20.      )
    
21.   )
    
22.   (princ)
    
23. )
    
24. 
    

(setq ss (ssget "x"))<br /> (defun ss1 (ss / i lst e)<br />   (setq i -1)<br />   (while (setq e (ssname ss (setq i (1+ i))))<br />     (setq lst (cons e lst))<br />   )<br />   (princ)<br /> )<br /> (defun ss2 (ss / i lst e)<br />   (setq i -1)<br />   (while (setq e (ssname ss (setq i (+ i 1))))<br />     (setq lst (cons e lst))<br />   )<br />   (princ)<br /> )<br /> (defun c:tt ()<br />   (XD::Benchmark<br />     '((ss1 ss)<br />       (ss2 ss)<br />      )<br />   )<br />   (princ)<br /> )<br /> <br />

测试：

1. 
   
2. 命令: (repeat 5 (c:tt))
   
3. Elapsed milliseconds / relative speed for 16384 iteration(s):
   
4. 
   
5.     (SS1 SS).....1625 / 1.04 <fastest>
   
6.     (SS2 SS).....1688 / 1 <slowest>
   
7. Elapsed milliseconds / relative speed for 8192 iteration(s):
   
8. 
   
9.     (SS2 SS).....1719 / 1.18 <fastest>
   
10.     (SS1 SS).....2032 / 1 <slowest>
    
11. Elapsed milliseconds / relative speed for 4096 iteration(s):
    
12. 
    
13.     (SS1 SS).....1000 / 1 <fastest>
    
14.     (SS2 SS).....1000 / 1 <slowest>
    
15. Elapsed milliseconds / relative speed for 4096 iteration(s):
    
16. 
    
17.     (SS2 SS).....1063 / 1.01 <fastest>
    
18.     (SS1 SS).....1078 / 1 <slowest>
    
19. Elapsed milliseconds / relative speed for 8192 iteration(s):
    
20. 
    
21.     (SS1 SS).....1750 / 1.02 <fastest>
    
22.     (SS2 SS).....1781 / 1 <slowest>
    
23. 
    

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基本上是1+要快

newer

那遍历选择集递增写法
(ssname ss (setq i (1+ i)))
和
(ssname ss i)
(setq i (1+ i))

两种写法哪个快？

1. (setq ss (ssget "x"))
   
2. 
   
3. (defun ss1 (ss / i lst e)
   
4.   (setq i -1)
   
5.   (while (setq e (ssname ss (setq i (1+ i))))
   
6.    )
   
7.   (princ)
   
8. )
   
9. 
   
10. (defun ss4 (ss / i lst e)
    
11.   (setq i 0)
    
12.   (while (setq e (ssname ss i))               
    
13.     (setq i (1+ i))
    
14.   )
    
15.   (princ)
    
16. )
    
17. 
    
18. 
    
19. (defun c:tt1 ()
    
20.   (XD::Benchmark
    
21.     '((ss1 ss)
    
22.       (ss4 ss)
    
23.      )
    
24.   )
    
25.   (princ)
    
26. )
    
27. 
    

(setq ss (ssget "x"))<br /> <br /> (defun ss1 (ss / i lst e)<br />   (setq i -1)<br />   (while (setq e (ssname ss (setq i (1+ i))))<br />    )<br />   (princ)<br /> )<br /> <br /> (defun ss4 (ss / i lst e)<br />   (setq i 0)<br />   (while (setq e (ssname ss i))               <br />     (setq i (1+ i))<br />   )<br />   (princ)<br /> )<br /> <br /> <br /> (defun c:tt1 ()<br />   (XD::Benchmark<br />     '((ss1 ss)<br />       (ss4 ss)<br />      )<br />   )<br />   (princ)<br /> )<br /> <br />

1. 
   
2. 命令: (repeat 5 (c:tt1))
   
3. Elapsed milliseconds / relative speed for 16384 iteration(s):
   
4. 
   
5.     (SS4 SS).....1406 / 1.11 <fastest>
   
6.     (SS1 SS).....1563 / 1 <slowest>
   
7. Elapsed milliseconds / relative speed for 8192 iteration(s):
   
8. 
   
9.     (SS1 SS).....1625 / 1.12 <fastest>
   
10.     (SS4 SS).....1828 / 1 <slowest>
    
11. Elapsed milliseconds / relative speed for 8192 iteration(s):
    
12. 
    
13.     (SS4 SS).....1735 / 1.09 <fastest>
    
14.     (SS1 SS).....1891 / 1 <slowest>
    
15. Elapsed milliseconds / relative speed for 8192 iteration(s):
    
16. 
    
17.     (SS4 SS).....1578 / 1.06 <fastest>
    
18.     (SS1 SS).....1672 / 1 <slowest>
    
19. Elapsed milliseconds / relative speed for 8192 iteration(s):
    
20. 
    
21.     (SS1 SS).....1672 / 1.04 <fastest>
    
22.     (SS4 SS).....1734 / 1 <slowest>
    
23. 
    

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基本上，是分开写的要快
(ssname ss i)
.....
(setq i (1+ i))


大家也可以在你的机器上测试下上面代码。