Printing of php-variables

Printing of variables

为什么要打印变量？因为在做开发的时候，我想看看现在这个值变成多少了，或者是否达到目的了。 所以需要打印变量来看看

PHP provides printing functions

echo(),print_r(),var_dump()使用中，echo 后面通常不加括号，而其他两个需要加、echo 比较使用来打印字符串和数字print_r 用来打印数组方便一些var_dump 所有类型都可以，打印变量的类型及其值    比如来了一个21，那到底是整型的21还是字符串的21，那么这个时候就比较适合用var_dump来打印，可以看得更清楚

Example:

  $a = 1;echo $a; output: 1//When you do not know what type such as the following Boolean value $ A = True;echo $a; output: 1//output is also 1$a = True;var_dump ($a); output: Boolean True// This is clear as $ A = Array (' Chen ', ' Li ', ' Wang ', ' Jin ');p rint_r ($a); output: Array ([0] = Chen [1] = [2] [+] = [+] = li [+] = Wang [3] = Ji N) Clear results for easy debugging Print_r typically prints an array using the  

PS: When precise debugging is required, use the print function selectively

Printing of php-variables