RegEx for both,integer和float

Question

我需要一个正则表达式来匹配两个,整数值以及浮点数(而浮点数有一个"."作为分隔符).这些数字总是在括号内,可能有一个前导"+".

什么应该是有效的:

• (1.0)
• (1)
• (9.9)
• (10000000)
• (15)

什么应该是无效的:

• 1.0 ---因为没有支架
• 5 ---因为没有支架
• (1,5)--- becaue","而不是"."
• (a)---因为没有数字
• (1 5)---因为不仅有一个数字
• (1 + 5)---因为......好吧......只是失败了
• [5] ---因为错误的括号

Answer 1

这应该适用于大多数perl,如正则表达式引擎:

/(\d+(\.\d+)?)/

Answer 2

不幸的是,目前接受的答案是有缺陷的(它将匹配"1a5",但它不匹配".5").所以我决定编写自己的Regex,以及一个廉价的Perl脚本来测试它.

要求

正则表达式将匹配整数或浮点数,前面带有+/-符号.我不关心E符号,所以我忽略了它.
nhahtdh提到"(5.)和(.6)":"5." 对我来说看起来不对,尾随时期没有任何意义.然而,".6"确实有效,因为前导期间表示正值<1(即,它是"0.6"的缩写).
最初(?=.)是确保空字符串不匹配.
作为奖励,我使用嵌套组,以便您可以轻松提取数字的不同部分:

• $ 1 =整数
• $ 2 =整数部分
• $ 3 =领先期间的分数部分
• $ 4 =分数部分

正则表达式

^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$

测试

$ perl -e 'use strict; use warnings; my $a = "1.0"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<1.0>
Integer:<1>
Fraction:<0>
$ perl -e 'use strict; use warnings; my $a = "1"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<1>
Integer:<1>
No fraction
$ perl -e 'use strict; use warnings; my $a = "9.9"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<9.9>
Integer:<9>
Fraction:<9>
$ perl -e 'use strict; use warnings; my $a = "10000000"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<10000000>
Integer:<10000000>
No fraction
$ perl -e 'use strict; use warnings; my $a = "+15"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<+15>
Integer:<15>
No fraction
$ perl -e 'use strict; use warnings; my $a = "1,5"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
NO MATCH
$ perl -e 'use strict; use warnings; my $a = "a"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
NO MATCH
$ perl -e 'use strict; use warnings; my $a = "1 5"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
NO MATCH
$ perl -e 'use strict; use warnings; my $a = "1+5"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
NO MATCH
$ perl -e 'use strict; use warnings; my $a = "5."; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
NO MATCH
$ perl -e 'use strict; use warnings; my $a = ".6"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<.6>
Integer:<>
Fraction:<6>
$ perl -e 'use strict; use warnings; my $a = ".5"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
MATCH
Float:<.5>
Integer:<>
Fraction:<5>
$ perl -e 'use strict; use warnings; my $a = "1a5"; if ($a =~ /^(?=.)([+-]?([0-9]*)(\.([0-9]+))?)$/) { print "MATCH\nFloat:<$1>\n"; print defined $2 ? "Integer:<$2>\n" : "No integer\n"; print defined $4 ? "Fraction:<$4>\n" : "No fraction\n"; } else { print "NO MATCH\n"; }'
NO MATCH

如果有什么我忽略了,请告诉我.

加成

执行大括号是微不足道的,只需将整个内容包装在ESCAPED括号中:

^\((?=.)([+-]?([0-9]*)(\.([0-9]+))?)\)$