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点号的疑惑解决思路

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Jun 13, 2016 am 10:22 AM

echophpquot

点号的疑惑

PHP code

<!--Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->echo '1+5='.1;  //为什么这么写会报错echo '1+5='. 1; //这句却能执行echo '1+5='.(1);//外面弄个括号却又行了

------解决方案--------------------
.和数字相邻时,会被识别为小数
而且小于1的小数可以省略开始的0，比如0.1写成.1是合法的

所以 '1+5'.1 被解析成两个相邻的常量,它们之间没有运算符,自然会报错.

类似的,1."abc"也会报错
------解决方案--------------------
.和数字相邻时,会被识别为小数，正如二楼所说。
echo '1+5='. 1; //这句却能执行。.在PHP是连接符的意思，是进行字符串连接的意思。

------解决方案--------------------
如hengyu654所说，"."直接接数字的时候并不作为字符串并置符处理，而是作为小数点处理
如下：

PHP code

echo "thr"."ee";           //输出字符串"three"echo "twe" . "lve";        //输出字符串"twelve"echo 1 . 2;                //输出字符串"12"echo 1.2;                  //输出数字1.2echo 1 ..2;                //输出字符串"10.2"<div class="clear">
                 
              
              
        
            </div>

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