lisp 里的format 

是输出的利器，不亚于c 语言的printf（）



我们主要展示 控制字符的行为：

注意 ~s  是输出 “” 的  ~a 是不输出的。

~10s  ~10a  指定宽带，空格后置

~10@a  ~10@s  指定宽带，空格前置


CL-USER> (format t "[~10a]" 'abc)
[ABC]
NIL
CL-USER> (format t "[~10a]" 'abc)
[ABC       ]
NIL
CL-USER> (format t "[~10s]" 'abc)
[ABC       ]
NIL
CL-USER> (format t "[~10s]" "abc")
["abc"     ]
NIL
CL-USER> (format t "[~10a " "abc")
[abc       
NIL
CL-USER> (format t "[~10@a]" "abc")
[       abc]
NIL
CL-USER> (format t "[~10@s]" "abc")
[     "abc"]
NIL
CL-USER>
再看一个

CL-USER> (format t "[~10,4a]" "abc")
[abc        ]
NIL

数一下【】 一共是11个字符，跟我们之前的说的不一致了，什么问题呢？
后面的4 这个参数，就是活每次扩展4个占位符
我们定义了10的宽度，去掉abc 3个宽带，还剩7个字符，一次补充4个，那么7个字符就要补充两次，就变成8个了，3+8=11 了。

明白了吧！！

继续下一个例子：

CL-USER> (format t "[~8,3,,'!a]" "abc")
[abc!!!!!!]
NIL
CL-USER> (format t "[~9,3,,'!a]" "abc")
[abc!!!!!!]
NIL
CL-USER> (format t "[~9,3,4,'!a]" "abc")
[abc!!!!!!]
NIL
CL-USER> (format t "[~10,3,4,'!a]" "abc")
[abc!!!!!!!]
NIL
CL-USER> (format t "[~10,3,4,'!a]" "abc")
[abc!!!!!!!]
NIL

这个模式可以指定填充用的字符。



---==================华丽分隔

下面这些就是数字的输出格式了
CL-USER> (format t " 1000 is x:[~x] " 1000)
 1000 is x: 3E8
NIL
CL-USER> (format t " 1000 is x:[~x] " 1000)
 1000 is x:[3E8]
NIL
CL-USER> (format t "1000 is binary: [~b]" 1000)
1000 is binary: [1111101000]
NIL
CL-USER> (format t "1000 is dicemal : [~d]" 1000)
1000 is dicemal : [1000]
NIL
CL-USER> (format t "1000 is float : [~f]" 1000)
1000 is float : [1000.0]
NIL
CL-USER> (format t "1000 is dicemal : [~:d]" 1000)
1000 is dicemal : [1,000]

CL-USER> (format t "1000 is dicemal : [~10d]" 1000)
1000 is dicemal : [      1000]
NIL
CL-USER> (format t "1000 is dicemal : [~10,xd]" 1000)
1000 is dicemal : [       3E8d]
NIL
CL-USER>
; No value
CL-USER> (format t "1000 is dicemal : [~10,'xd]" 1000)
1000 is dicemal : [xxxxxx1000]
NIL
CL-USER> (format t "[~4f]" 3.1415926)
[3.14]
NIL
CL-USER> (format t "[~6f]" 3.1415926)
[3.1416]
NIL
CL-USER>
; No value
CL-USER>

CL-USER> (format t "percent : [~,,2f]" 0.77)
percent : [77.0]
NIL
CL-USER> (format t "percent : [~,,2f%]" 0.77)
percent : [77.0%]
NIL
CL-USER> (format t "$2.3 is [~$]" 2.3)
$2.3 is [2.30]
NIL
CL-USER>

恩，数字就先这些吧，

================

下面看看控制字符换行符
~%
~&


CL-USER> (format t " newline ~%  and ~&" )
 newline
  and
NIL
CL-USER> (format t " newline ~%  and ~& xxx" )
 newline
  and
 xxx
NIL
CL-USER>
; No value
CL-USER> (format t " newline ~&  and ~% xxx" )
 newline
  and
 xxx
NIL
CL-USER> (format t " newline ~&  and ~%" )
 newline
  and
NIL
CL-USER>

～％　是一定要给一个新行的
～＆ 则不一定每次都给一个新行，只在必要的时候给一个。
CL-USER> (progn
       (format t " newline  and ~%" )
       (format t "~& newline  and ~%")
       )
 newline  and
 newline  and
NIL
CL-USER> (progn
       (format t " newline  and ~%" )
       (format t "~% newline  and ~%")
       )
 newline  and

 newline  and
NIL
CL-USER>


======================
继续

~t  是定义列 里面的数字跟前面一个意思



CL-USER> (defun random-animal ()
(nth (random 5) '("dog" "tick" "tiger" "walrus" "kangaroo")))
RANDOM-ANIMAL
CL-USER> (loop repeat 10
do (format t "~5t~a ~15t~a ~25t~a~%"
(random-animal)
(random-animal)
(random-animal)))
     kangaroo  dog       kangaroo
     kangaroo  dog       kangaroo
     kangaroo  tick      walrus
     tick      dog       tiger
     tick      dog       tiger
     kangaroo  kangaroo  kangaroo
     kangaroo  kangaroo  dog
     walrus    kangaroo  kangaroo
     kangaroo  dog       tiger
     walrus    kangaroo  tick
NIL

在继续
~30<  ~>   标识构建一个30字符宽的块（block）

CL-USER> (loop repeat 10
do (format t "~30<~a~;~a~;~a~>~%"
(random-animal)
(random-animal)
(random-animal)))
dog         dog          tiger
dog      kangaroo       walrus
walrus    kangaroo    kangaroo
tiger      walrus       walrus
dog       tick        kangaroo
tick      kangaroo      walrus
walrus       tick       walrus
walrus      walrus       tiger
tick       tiger        walrus
dog          dog          tick
NIL


=====================
再继续 ：

:@　　意思是居中打印

CL-USER> (loop repeat 10
do (format t "~30:@<~a~;~a~;~a~>~%"
(random-animal)
(random-animal)
(random-animal)))
   tiger    tiger    tiger   
   tiger   walrus   walrus   
  walrus  kangaroo   walrus  
   kangaroo   tick   walrus  
   walrus    dog    walrus   
   walrus    dog    walrus   
    dog    tiger    tiger    
  walrus   kangaroo   tiger  
   tick   kangaroo   tiger   
   kangaroo    tick    dog   
NIL
CL-USER>



====================

再继续 ：
这个一看就明白了，不多说了

CL-USER> (defparameter *animals* (loop repeat 10 collect (random-animal)))
*ANIMALS*
CL-USER> *animals*
("walrus" "kangaroo" "tick" "kangaroo" "tiger" "kangaroo" "walrus" "tiger"
 "kangaroo" "tiger")

CL-USER> (format t "~{I see a ~a! ~}" *animals*)

I see a walrus! I see a kangaroo! I see a tick! I see a kangaroo! I see a tiger! I see a kangaroo! I see a walrus! I see a tiger! I see a kangaroo! I see a tiger!
NIL

CL-USER> (format t "~{I see a ~a!~% ~}" *animals*)
I see a walrus!
 I see a kangaroo!
 I see a tick!
 I see a kangaroo!
 I see a tiger!
 I see a kangaroo!
 I see a walrus!
 I see a tiger!
 I see a kangaroo!
 I see a tiger!
 
CL-USER> (format t "~{I see a ~a... or was it a ~a?~%~}" *animals*)
I see a walrus... or was it a kangaroo?
I see a tick... or was it a kangaroo?
I see a tiger... or was it a kangaroo?
I see a walrus... or was it a tiger?
I see a kangaroo... or was it a tiger?



====================
再来一个bt 一点的

CL-USER> (format t "|~{~<|~%|~,33:;~2d ~>~}|" (loop for x below 100 collect x))
| 0  1  2  3  4  5  6  7  8  9 |
|10 11 12 13 14 15 16 17 18 19 |
|20 21 22 23 24 25 26 27 28 29 |
|30 31 32 33 34 35 36 37 38 39 |
|40 41 42 43 44 45 46 47 48 49 |
|50 51 52 53 54 55 56 57 58 59 |
|60 61 62 63 64 65 66 67 68 69 |
|70 71 72 73 74 75 76 77 78 79 |
|80 81 82 83 84 85 86 87 88 89 |
|90 91 92 93 94 95 96 97 98 99 |
NIL

说明一下

~{  ~}  这一对是循环 ，对应于loop 里面的控制字符是要循环控制的

~< ~>  这个前面看过了，生成一个块结构
|~%|   新行 没有问题
~：； 这个也是新行  ，前面那个33 是是说，这一行的长度到了33字符，就要换行了。

~2d 这个没得说了 2位数字。



好了，也差不多了，够长的了。