Usage and precautions of print keyword in PHP

Usage and precautions for the print keyword in PHP

PHP is a server-side scripting language widely used in web development. It has concise syntax and powerful functions and can easily generate dynamic web pages. content. In PHP, print is a keyword that is used to print the values ​​of strings and variables. This article will introduce the usage of the print keyword and what needs to be paid attention to.

1. Basic usage of the print keyword
In PHP, you can use the print keyword to output the values ​​of strings and variables to the browser or command line. The general syntax of print is as follows:
print expression;

where expression represents the string or variable to be output.

The print statement does not require the use of parentheses, but if you want to output multiple strings or variable values, you can use parentheses to enclose them, such as:
print ("Hello, ");
print "World!";

print can also be used as a function, accepting a parameter and outputting the value of the parameter. For example:
$message = "Hello, World!";
print($message);

2. Notes on the print keyword

1. print keyword The difference with the echo keyword:
   In PHP, in addition to using the print keyword, you can also use the echo keyword to output the values ​​of strings and variables. Their functionality is basically the same, but they differ in syntax. Unlike the echo keyword, the print keyword has a return value. It returns a value of 1, so it can be used as part of an expression. Echo has no return value and can only be used to output content.
2. Use print to output HTML code:
   When you need to output HTML code in PHP, you can use the print keyword. For example:
   print "

   Welcome to my website!

   ";
3. When outputting the value of a variable, the print keyword can omit the brackets:
   If you want to output the value of the variable value, you can omit the parentheses after the print keyword. For example:
   $message = "Hello, World!";
   print $message;
4. Use of print and .= operator:
   In PHP, you can use the .= operator Appends one string to the end of another string. When using the print keyword to output a multi-line string, you can use the .= operator to concatenate multiple strings. For example:
   $message = "Hello, ";
   $message .= "World!";
   print $message;
5. When used to output an array, the print keyword can only Output Array:
   If you use the print keyword to output an array, it will only output the string "Array" and not the specific contents of the array. To output the contents of an array, you can use the print_r() function or the var_dump() function.
6. The print keyword can use commas to connect multiple parameters:
   The print keyword can accept multiple parameters and separate them with commas when outputting. For example:
   print "Hello", "World!";

To sum up, this article introduces the basic usage and precautions of the print keyword in PHP. By using the print keyword, you can easily output the values ​​of strings and variables, and output multiple lines as needed or use commas to connect multiple parameters. When using the print keyword, you need to pay attention to the differences from the echo keyword, as well as the special circumstances when outputting HTML code and arrays. I hope this article can help PHP developers understand and use the print keyword.

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