Introduction
xv
Notice that the print line ends with a semicolon. Nearly all lines of code in a
PHP script end with a semicolon. Exceptions include PHP logic such as if and
for statements. We will get into this later.
Variables
Variables are used to store data in a convenient way to use and reuse throughout a
PHP document. We will use PHP variables quite a bit in the examples in this book.
Declaring a static variable is very simple. Variables always start with $ and should
contain only lowercase text.
Let’s declare a simple variable. Open up the PHP file you just created and delete
the following line:
print '<h1>Hello World!</h1>';
Replace it with this:
$variable = "This is a variable.";
The variable entitled $variable can now be used throughout the document.
To see how this works let’s do a couple of things to the variable. First let’s just print
it out. We will be printing out variables throughout this book:
print '<h1>' . $variable . '</h1>';
Save the PHP file and open it in your browser. You should see plain text that
says: This is a variable.
You can achieve the same efect by using the echo command:
echo $variable;
We will employ echo a lot in this book to ensure we have our variables correct.
Commenting Out Code
While we work on our scripts, it will sometimes be necessary to disable certain
lines of code. This is a common coding need. This is done by commenting out code.
Let’s say that while we are working on a script, we are using the echo command
quite a bit. This is useful for debugging purposes, but for production we don’t want
some of those variables echo’d out to the browser.
To comment out code we can do one of two things. We can comment out a single
line of code by preceding the line with two forward slashes:
//echo $variable;
剩余151页未读，继续阅读
ramissue
- 粉丝: 354
- 资源: 1487
我的内容管理
展开
最新资源
- 计算机人脸表情动画技术发展综述
- 关系数据库的关键字搜索技术综述：模型、架构与未来趋势
- 迭代自适应逆滤波在语音情感识别中的应用
- 概念知识树在旅游领域智能分析中的应用
- 构建is-a层次与OWL本体集成：理论与算法
- 基于语义元的相似度计算方法研究：改进与有效性验证
- 网格梯度多密度聚类算法：去噪与高效聚类
- 网格服务工作流动态调度算法PGSWA研究
- 突发事件连锁反应网络模型与应急预警分析
- BA网络上的病毒营销与网站推广仿真研究
- 离散HSMM故障预测模型：有效提升系统状态预测
- 煤矿安全评价：信息融合与可拓理论的应用
- 多维度Petri网工作流模型MD_WFN：统一建模与应用研究
- 面向过程追踪的知识安全描述方法
- 基于收益的软件过程资源调度优化策略
- 多核环境下基于数据流Java的Web服务器优化实现提升性能
资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！
点击此处反馈
