Chapter 4_PHP Basic Syntax_PHP Tutorial

1. The first PHP program

<span 1</span> <span //</span><span 弱爆了有木有</span>
<span 2</span> <?<span php
</span><span 3</span>     <span echo</span> "<span Hello PHP!';
</span><span 4</span> ?>

2.PHP supports a total of 8 basic data types, including 4 scalar types: boolean (Boolean type), integer (integer type), float (floating point type, also called double), string (string), 2 composite types: array (array), object (object), 2 special types: resource (resource), NULL (empty type)

3. The function var_dump can be used to print relevant information about variables.

<span 1</span> <?<span php
</span><span 2</span>     <span var_dump</span>((bool) <span false</span><span );
</span><span 3</span>     <span var_dump</span>((bool) 0<span );
</span><span 4</span>     <span var_dump</span>((bool) 0.0<span );
</span><span 5</span>     <span var_dump</span>((bool) ''<span );
</span><span 6</span>     <span var_dump</span>((bool) "0"<span );
</span><span 7</span>     <span var_dump</span>((bool) <span array</span><span ());
</span><span 8</span>     <span var_dump</span>((bool) <span NULL</span><span );
</span><span 9</span> ?>

4. About integers.

In 32-bit operating systems, the valid range of integers is -2147483648~+2147483647. If it exceeds this range, it will be interpreted as a floating point number (float) by the PHP engine.

Add 0 in octal and 0x in hexadecimal (the number 0 instead of the letter O)

<span  1</span> <?<span php
</span><span  2</span>     <span $dec_int</span>=63<span ;
</span><span  3</span>     <span var_dump</span>(<span $dec_int</span><span );
</span><span  4</span>     
<span  5</span>     <span $oct_int</span>=077<span ;
</span><span  6</span>     <span var_dump</span>(<span $oct_int</span><span );
</span><span  7</span>     
<span  8</span>     <span $hex_int</span>=0x3f<span ;
</span><span  9</span>     <span var_dump</span>(<span $hex_int</span><span );
</span><span 10</span> ?>

5. String type

There are three ways to define strings, namely single quotes ('), double quotes (") and delimiters (.

<span 1</span> <?<span php
</span><span 2</span>     <span $name</span>='麦兜'<span ;
</span><span 3</span>     <span $age</span>=19<span ;
</span><span 4</span>     <span echo</span> '本人大名$name，年方$age'<span ;
</span><span 5</span>     <span echo</span> '<p>'<span ;
</span><span 6</span>     <span echo</span> "本人大名<span $name</span>,年方<span $age</span>"<span ;
</span><span 7</span> ?>

The use of delimiters is as follows:

<span 1</span> <?<span php
</span><span 2</span>     <span echo</span> <<<<span MY_STR
</span><span 3</span> <span     我是PHP初学者
</span><span 4</span> <span MY_STR;　　　　　　//最后结尾的标识符前面不能有空格或者缩进，必须顶咯
</span><span 5</span> ?>

6. Object type

<span  1</span> <?<span php
</span><span  2</span> <span class</span><span  Person {
</span><span  3</span>     <span public</span> <span $name</span><span ;
</span><span  4</span>     <span private</span> <span $age</span><span ;
</span><span  5</span>     
<span  6</span>     <span function</span> Person(<span $name</span>,<span $age</span><span ){
</span><span  7</span>         <span $this</span>->name=<span $name</span><span ;
</span><span  8</span>         <span $this</span>->age=<span $age</span><span ;
</span><span  9</span> <span     }
</span><span 10</span>     
<span 11</span>     <span function</span><span  getInfo(){
</span><span 12</span>         <span echo</span> '我叫'.<span $this</span>->name.'<br>我今年'.<span $this</span>->age.'岁了'<span ;
</span><span 13</span> <span     }
</span><span 14</span> <span }
</span><span 15</span>     <span $boy</span> = <span new</span> Person("kimi",5<span );
</span><span 16</span>     <span $boy</span>-><span getInfo();
</span><span 17</span> ?>    

7. Type conversion

　print_r() Displays easy-to-understand information about a variable. If given is string, integer or float, the variable will be printed value itself. If array is given, the keys and elements

will be displayed in a certain format.

　

<span  1</span> <?<span php
</span><span  2</span>     <span $temp_var</span>=3.141592653<span ;
</span><span  3</span>     <span $var1</span>=(<span string</span>)<span $temp_var</span><span ;
</span><span  4</span>     <span echo</span> "<p><span $var1</span>"<span ;
</span><span  5</span>     
<span  6</span>     <span $temp_var</span>='Kimi'<span ;
</span><span  7</span>     <span $var2</span>=(<span array</span>)<span $temp_var</span><span ;
</span><span  8</span>     <span echo</span> '<p>'<span ;
</span><span  9</span>     <span print_r</span>(<span $var2</span><span );
</span><span 10</span>     
<span 11</span>     <span $temp_var</span>='Cindy'<span ;
</span><span 12</span>     <span $var3</span>=(<span unset</span>)<span $temp_var</span><span ;
</span><span 13</span>     <span echo</span> '<p>'<span ;
</span><span 14</span>     <span var_dump</span>(<span $var3</span><span );
</span><span 15</span> ?>

http://www.bkjia.com/PHPjc/626630.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/626630.htmlTechArticle1. The first PHP program? " ? 2.PHP supports a total of 8 basic data rationales, including 4 Scalar types: boolean (Boolean type), integer (integer type), float (floating point type, also called double), s...