Summary of steps to use commas and periods for echo in PHP

This time I will bring you a summary of the steps for using commas and dots in echo in php. What are the precautions for using commas and dots in echo in php? The following is a practical case. Get up and take a look.

The example is as follows:

<?php //点和逗号的测试,涉及到字符串的强制转换
echo 1+5;
echo "<br /><br>";
echo '1+5='."1+5"."<br>";
echo '1+5='."5+1","<br><br>";	
echo '1+5=',1,"<br>";			//用逗号，不需要空格
echo '1+5='. 1,"<br>";		//用连接符，需要空格，否则报错
echo '1+5=',100+200,"<br><br>"; //用逗号，常用于输出多个变量，不影响输出
//省去了字符串拼接的步骤，理论上在 echo 的时候用“逗号”会快一点。
//换成用连接符，注意了，看以下测试：
echo '注意了！<br>';		
echo '1+5='. 100,"<br>";		//注意 .和100之间需要空格，否则报错
echo '1+5='. 200,"<br>";				
echo '1+5='. 100+200,"<br>";	//此处结果开始异常了
echo '1+5='. 200+100,"<br>";
echo ('1+5='. 200)+100,"<br>"; 	//从与上面的结果相同可以看出，连接符的优先级高于运算符
echo "<br>";		
//先来看看字符串的强制转换
echo (int)'abc1';	echo "<br>";	
echo (int)'1abc';	echo "<br>";
echo (int)'22abc';	echo "<br><br>";
//结果：将一个字符串强制转换成一个数字，PHP会去搜索这个字符串的开头，
//如果开头是数字就转换，如果不是就直接返回0.
//回到测试的问题
echo '结果分析：';
echo '1+5='. 100+200,"<br>";
/* 程序是这样执行的，
 * 先连接 '1+5='.100 结果是字符串 '1+5=100'，
 * 然后执行运算，字符串要与数字进行运算会被系统强制转换，字符串'1+5=100'转换后的值就是1，
 * 最后1+200=201.
 */
 /* 用逗号为什么没问题呢？
	手册上说了：用逗号是multiple parameters .也就是说是多参数，
	换句话说，逗号分隔开的就相当于是N个参数.也就是说把echo当个函数用，
	这样的话，echo会对每个参数先进行计算，最后再进行分别输出，所以我们用逗号就不存在上面的问题了
 */
?>

The result is as follows:

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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