全部博文（362）
分类：
2010-09-28 16:52:53
整型还是字符串?
1 #!/bin/bash
2 # int-or-string.sh: 整型还是字符串?
3
4 a=2334 # 整型.
5 let "a += 1"
6 echo "a = $a " # a = 2335
7 echo # 还是整型.
8
9
10 b=${a/23/BB} # 将"23"替换成"BB".
11 # 这将把变量b从整型变为字符串.
12 echo "b = $b" # b = BB35
13 declare -i b # 即使使用declare命令也不会对此有任何帮助.
14 echo "b = $b" # b = BB35
15
16 let "b += 1" # BB35 + 1 =
17 echo "b = $b" # b = 1
18 echo
19
20 c=BB34
21 echo "c = $c" # c = BB34
22 d=${c/BB/23} # 将"BB"替换成"23".
23 # 这使得变量$d变为一个整形.
24 echo "d = $d" # d = 2334
25 let "d += 1" # 2334 + 1 =
26 echo "d = $d" # d = 2335
27 echo
28
29 # null变量会如何呢?
30 e=""
31 echo "e = $e" # e =
32 let "e += 1" # 算术操作允许一个null变量?
33 echo "e = $e" # e = 1
34 echo # null变量将被转换成一个整型变量.
35
36 # 如果没有声明变量会怎样?
37 echo "f = $f" # f =
38 let "f += 1" # 算术操作能通过么?
39 echo "f = $f" # f = 1
40 echo # 未声明的变量将转换成一个整型变量.
41
42
43
44 # 所以说Bash中的变量都是不区分类型的.
45
46 exit 0 |
