php7 first day of variables and output, heredoc summary

php7 first day of variables and output, heredoc summary, the definition of variables prior to learning a language, the relationship between the variable output

1, the definition of variables
php begins with $ $ a = "111212";

    变量名 字母，下划线，数字，横杠 
    不能以数字开头
    区分大小写

2，输出

echo "www.96net.com.cn" 输出一个字符或者多个字符

print () output a character

print_r () function is used to print variable, displayed in a form more understandable

var_dump() 打印输出

3,PHP heredoc

PHP EOF(heredoc)是一种在命令行shell（如sh、csh、ksh、bash、PowerShell和zsh）和程序语言（像Perl、PHP、Python和Ruby）里定义一个字符串的方法.