search
HomeBackend DevelopmentPHP ProblemWhat are the differences in php output?

The differences in php output are: 1. echo returns void and does not return a value; 2. echo speed is faster than print; 3. print_r function prints easy-to-understand information about variables; 4. The printf() function returns a formatted string; 5. The sprintf function writes the formatted string into a variable instead of outputting it; 6. The var_dump function is used for debugging.

What are the differences in php output?

The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer

The six output methods in php Difference

php output echo, print , print_r , printf , Comparison of the differences between sprintf and var_dump.

1. echo

echo() is actually not a function, but a php statement, so you don’t need to It uses parentheses. However, if you wish to pass more than one argument to echo(), then using parentheses will cause a parsing error. Moreover, echo returns void and does not return a value, so it cannot be used to assign values.

<?php

$a = echo("words"); // 错误!不能用来赋值

echo "words"; // 55nav

echo ("words"); // 55nav

echo ("apple","bear"); //发生错误,有括号不能传递多个参数

echo "alice","bill","cart", "daring";  // 不用括号的时候可以用逗号隔开多个值, 会输出 alicebillcartdaring  不管是否换行,最终显示都是为一行

$fistname="alice";

echo "$fistname com"; // 如果 $firstname = "alice", 则会输出 alice com.

echo &#39;$firstname com&#39;; // 由于使用单引号,所以不会输出$firstname的值,而是输出 $firstname com

?>

2、print

print() has the same usage as echo(), but echo is faster than print A little faster. It's actually not a function either, so you don't need to use parentheses on it.

However, if you wish to pass more than one argument to print(), then using parentheses will cause a parsing error.

Note that print always returns 1, which is different from echo.

That is, you can use print to assign values, but it has no practical meaning. .

1 <?php 
2 
3 $a = print("alice"); // 这个是允许的
4 
5 echo $a; // $a的值是1

#3. print_r function

The print_r function prints easy-to-understand information about variables.

Syntax:

mixed print_r ( mixed $expression [, bool return ] )

If the variable is string, integer or float, its value will be output directly. If the variable is an array, a formatted array will be output for easy reading, that is, the format corresponding to key and value.

Similar to object objects.

print_r has two parameters. The first is a variable and the second can be set to true. If set to true, a string will be returned, otherwise a Boolean value TRUE## will be returned. #.

<?php

$a="alice";

$c = print_r($a);

echo $c;  // $c的值是TRUE

$c = print_r($a,true);

echo $c; // $c的值是字符串alice

$d = [1,2,3,4];

print_r($d); // Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 )

4. printf function

printf() function returns a formatted string .

Syntax:

printf(format,arg1,arg2,arg)

Parameter format It is the conversion format, starting with the percent sign ("%") and ending with the conversion character.

The following are possible format values: * %% – Returns the percent sign

* %b – 二进制数* %c – 依照 ASCII 值的字符* %d – 带符号十进制数* %e – 可续计数法(比如 1.5e+3)* %u – 无符号十进制数* %f – 浮点数(local settings aware)* %F – 浮点数(not local settings aware)* %o – 八进制数* %s – 字符串* %x – 十六进制数(小写字母)* %X – 十六进制数(大写字母)arg1, arg2, arg++ 等参数将插入到主字符串中的百分号 (%) 符号处。该函数是逐步执行的,在第一个 % 符号中,插入 arg1,在第二个 % 符号处,插入 arg2,依此类推。

If there are more than % signs arg parameter, you must use placeholders. Placeholders are inserted after the % sign and consist of numbers and "\$".

You can use numbers to specify the displayed parameters. Please see the example for details.

<?php

printf("My name is %s %s。","alice", "com"); // My name is alice com。

printf("My name is %1\$s %1\$s","alice", "com"); // 在s前添加1\$或2\$.....表示后面的参数显示的位置,此行输出 My name is alice alice因为只显示第一个参数两次。

printf("My name is %2\$s %1\$s","alice", "com"); // My name is com alice

?>

5、sprintf函数

此函数使用方法和printf一样,唯一不同的就是该函数把格式化的字符串写入一个变量中,而不是输出来。

<?php

sprintf("My name is %1\$s %1\$s","alice", "com");  //你会发现没有任何东西输出的。

$out = sprintf("My name is %1\$s %2\$s","alice", "com");

echo $out;  //输出 My name is alice com

6、var_dump函数

功能: 输出变量的内容、类型或字符串的内容、类型、长度。常用来调试。

1 var_dump(&#39;hello&#39;); // string(5) "hello"

 推荐学习:《PHP视频教程

The above is the detailed content of What are the differences in php output?. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
ACID vs BASE Database: Differences and when to use each.ACID vs BASE Database: Differences and when to use each.Mar 26, 2025 pm 04:19 PM

The article compares ACID and BASE database models, detailing their characteristics and appropriate use cases. ACID prioritizes data integrity and consistency, suitable for financial and e-commerce applications, while BASE focuses on availability and

PHP Secure File Uploads: Preventing file-related vulnerabilities.PHP Secure File Uploads: Preventing file-related vulnerabilities.Mar 26, 2025 pm 04:18 PM

The article discusses securing PHP file uploads to prevent vulnerabilities like code injection. It focuses on file type validation, secure storage, and error handling to enhance application security.

PHP Input Validation: Best practices.PHP Input Validation: Best practices.Mar 26, 2025 pm 04:17 PM

Article discusses best practices for PHP input validation to enhance security, focusing on techniques like using built-in functions, whitelist approach, and server-side validation.

PHP API Rate Limiting: Implementation strategies.PHP API Rate Limiting: Implementation strategies.Mar 26, 2025 pm 04:16 PM

The article discusses strategies for implementing API rate limiting in PHP, including algorithms like Token Bucket and Leaky Bucket, and using libraries like symfony/rate-limiter. It also covers monitoring, dynamically adjusting rate limits, and hand

PHP Password Hashing: password_hash and password_verify.PHP Password Hashing: password_hash and password_verify.Mar 26, 2025 pm 04:15 PM

The article discusses the benefits of using password_hash and password_verify in PHP for securing passwords. The main argument is that these functions enhance password protection through automatic salt generation, strong hashing algorithms, and secur

OWASP Top 10 PHP: Describe and mitigate common vulnerabilities.OWASP Top 10 PHP: Describe and mitigate common vulnerabilities.Mar 26, 2025 pm 04:13 PM

The article discusses OWASP Top 10 vulnerabilities in PHP and mitigation strategies. Key issues include injection, broken authentication, and XSS, with recommended tools for monitoring and securing PHP applications.

PHP XSS Prevention: How to protect against XSS.PHP XSS Prevention: How to protect against XSS.Mar 26, 2025 pm 04:12 PM

The article discusses strategies to prevent XSS attacks in PHP, focusing on input sanitization, output encoding, and using security-enhancing libraries and frameworks.

PHP Interface vs Abstract Class: When to use each.PHP Interface vs Abstract Class: When to use each.Mar 26, 2025 pm 04:11 PM

The article discusses the use of interfaces and abstract classes in PHP, focusing on when to use each. Interfaces define a contract without implementation, suitable for unrelated classes and multiple inheritance. Abstract classes provide common funct

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
3 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Best Graphic Settings
3 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. How to Fix Audio if You Can't Hear Anyone
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
WWE 2K25: How To Unlock Everything In MyRise
1 months agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment