Getting Started with PHP: Start Learning from Basic Syntax

PHP is a widely used server-side scripting language that can be used in conjunction with HTML to create a variety of dynamic websites. PHP language is easy to learn and use, rich in resources, and is one of the preferred languages ​​for website developers. In the process of learning PHP, you must first master the basic grammar of the language. Here I will tell you the basic grammar of PHP, hoping to help readers learn PHP better.

1. Basic PHP syntax

PHP’s syntax is similar to the syntax of many other languages, such as Perl and C, making it easy to learn. In PHP, all statements end with a semicolon, making it clearer when writing code. The following are some common PHP syntax:

1. Output: Use the echo or print keywords to output content to the browser.

For example:

<?php
    echo "Hello World!";
    print "Hello World!";
?>

The results displayed by the above code in the browser are "Hello World!".

2. Comments: Comments in PHP start with "//" or "#". You can add comments to the script to facilitate yourself or others to understand the code.

For example:

<?php 
    # This is a comment
    // This is another comment
?>

3. Variables: In PHP, variables start with the "$" symbol and can contain letters, numbers, and underscores. Variable names must start with a letter or underscore, not a number.

For example:

<?php
    $name = "Tom";
    $age = 25;
    $height = 170.5;
?>

In the above code, $name is a string variable, $age is an integer variable, and $height is a floating point variable.

4. Data types: PHP supports a variety of data types, including integers, floating point, Boolean, strings, arrays, objects, NULL and resources.

For example:

<?php
    $num1 = 10; // 整型
    $num2 = 3.14; // 浮点型
    $truth = true; // 布尔型
    $name = "John"; // 字符串
    $arr = array("苹果", "香蕉", "橙子"); // 数组
    $obj = new stdClass(); // 对象
    $nothing = null; // NULL
?>

5. Operators: In PHP, you can use many various types of operators, such as arithmetic operators, comparison operators and logical operations Fu et al. You can use these operators to perform various calculations, and using these operators in your code can make your code cleaner.

For example:

<?php
    $num1 = 10;
    $num2 = 3;
    $sum = $num1 + $num2; // 加法运算符，值为13
    $diff = $num1 - $num2; // 减法运算符，值为7
    $prod = $num1 * $num2; // 乘法运算符，值为30
    $quo = $num1 / $num2; // 除法运算符，值为3.33...
    $mod = $num1 % $num2; // 取模运算符，值为1
    $cond = ($num1 > $num2); // 比较运算符，值为true
    $logic = ($num1 > 0) && ($num2 < 5); // 逻辑运算符，值为false
?>

6. String concatenation: In PHP, you can use the period (".") to concatenate strings and merge multiple strings into one.

For example:

<?php
    $greeting = "Hello";
    $name = "Tom";
    $message = $greeting . $name; // $message的值是"HelloTom"
?>

7. Conditional statements: In PHP, you can use conditional statements to execute blocks of code as needed. Conditional statements include if, else, switch and other structures, which can execute different code blocks based on the value of the variable.

For example:

<?php
    $num = 10;
    if ($num > 0){
        echo "这个数是正数";
    }
    elseif ($num == 0){
        echo "这个数是零";
    }
    else{
        echo "这个数是负数";
    }
?>

The above code outputs "This number is a positive number" when the value of the variable $num is a positive number, and outputs "This number is a positive number" when the value of the variable is zero. Zero", when the value of the variable is a negative number, it outputs "This number is a negative number".

8. Loop statement: In PHP, you can use a loop statement to repeatedly execute a block of code. Loop statements include while, do-while, for, foreach and other structures, which can execute different code blocks as needed.

For example:

<?php
    for ($i = 1; $i <= 10; $i++){
        echo $i." ";
    }
    echo "<br>";
    $j = 1;
    while ($j <= 10){
        echo $j." ";
        $j++;
    }
?>

The above code uses for and while loops to output numbers from 1 to 10 respectively.

9. Functions: In PHP, you can use functions to package reusable code. A function definition begins with the "function" keyword, can accept any number of parameters, and can return a value.

For example:

<?php
    function square($num){
        return $num * $num;
    }
    $result = square(5);
    echo $result; // 输出25
?>

The above code defines a function named "square", which accepts a parameter, returns the square value of the parameter, and then calls the function and outputs return value.

2. Conclusion

These basic PHP syntax must be mastered by beginners. Subsequent PHP learning is inseparable from an in-depth mastery and understanding of these basic knowledge, which plays a decisive role in writing better PHP code. In the process of learning PHP, don't rush for success, but have a solid foundation, be brave enough to try, keep practicing, gradually hone your skills in practice, and eventually become an excellent PHP programmer.

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