在Perl中,字符串比较和数字比较是由不同的运算符来完成的:
- 数字比较运算符: <,>,<=,>=,==,!=
- 字符串比较运算符: lt,gt,le,ge,eq,ne
- cmp: 比较字符串,返回 -1,0 或者 1。
- <=>: 比较数字,返回 -1,0 或者 1。
- =~:用正则表达式来匹配,匹配的话返回True。
- !~:和 =~ 相反,不匹配返回True。
我有好几次都用错了,结果浪费了很多时间在调试上面。
#!/usr/bin/env perl use strict; use warnings; my $num1 = 1; my $num2 = 1.0; my $two_numbers = "$num1 and $num2"; my $str1 = "1abc"; my $str2 = "1xyz"; my $two_strings = "$str1 and $str2"; print "Compare two numbers using !=\n"; if ($num1 != $num2) { print "$two_numbers are not equal\n"; } else { print "$two_numbers are equal\n"; } print "Compare two strings using !=: get wrong result\n"; if ($str1 != $str2) { print "$two_strings are not equal\n"; } else { print "$two_strings are equal\n"; } print "Compare two numbers using ne\n"; if ($num1 ne $num2) { print "$two_numbers are not equal\n"; } else { print "$two_numbers are equal\n"; } print "Compare two strings using ne\n"; if ($str1 ne $str2) { print "$two_strings are not equal\n"; } else { print "$two_strings are equal\n"; }
Compare two numbers using != 1 and 1 are equal Compare two strings using !=: get wrong result Argument "1xyz" isn't numeric in numeric ne (!=) at compare_operators.pl line 23. Argument "1abc" isn't numeric in numeric ne (!=) at compare_operators.pl line 23. 1abc and 1xyz are equal Compare two numbers using ne 1 and 1 are equal Compare two strings using ne 1abc and 1xyz are not equal
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 dio@foxmail.com 举报,一经查实,本站将立刻删除。