1.打印字符串
三种打印方式:
irb(main):001:0> p 'hello' "hello" => "hello" irb(main):002:0> puts 'hello' hello => nil irb(main):003:0> print 'hello' hello=> nil
会发现print打印不带换行,puts和p打印带换行(print "hello\n"实现换行)
另外会发现p打印返回打印的字符串,print和puts返回nil
2.heredoc
语法:
<<结束标志 # here docs 结束标志
sample:
print <<EOF # heredoc hello world EOF print <<'EOF' # 同上 hello world EOF print <<`EOF` # 执行外部命令 echo 'hello world' EOF print <<"foo", <<"bar" # 你可以把这些heredoc堆积起来 I said foo. foo I said bar. bar
输出
hello world hello world hello world I said foo. I said bar.
3.BEGIN和END
BEGIN:声明将在程序的开始调用的代码
END:声明将在程序的最后调用的代码
print 'hello world' BEGIN{ print 'begin code' } END{ print 'end code' }
4.程序注释
单行注释:
# comments
多行注释:
=begin # comments # comments # comments =end