Detailed introduction to PHP print output function summary

This article summarizes and introduces 7 types of php commonly used print output functions, which are echo, print, printf, sprintf, print_r, var_dump, die. I hope you can learn from them. php can help

This article has been to learn all the functions used to output information in PHP, classify and compare them to learn their similarities and differences, and master the necessary skills in daily development.

Development must require debuggingcode, and PHP debugging code cannot be single-step debugged through development software such as Xcode like iOS. Therefore, people who develop PHP usually Use the output function to print relevant prompt information to debug the code.

A step-by-step explanation of commonly used print output functions in PHP

echo

The echo function can output multiple characters at the same time The string takes multiple parameters, but parentheses are not required and there is no return value. However, there is no problem if you bring parentheses, so the function requires parentheses:

echo &#39;标哥的技术博客<br>&#39;;
echo (&#39;echo也可以带括号<br>&#39;);

I believe the echo function is the most commonly used printing function!

print

The print function can only output one string at a time, can only take one parameter, requires parentheses and will have a return value. Returns false when its execution fails.

print(&#39;www.huangyibiao.com<br>&#39;);

The print function is also used quite a lot, for printing information, but it is not as convenient as echo, but it has its uses!

printf

The printf function takes two parameters. The first parameter is to specify the output format, and the second parameter is to output variable. The output format is:

%s: by string;
%d: by integer;
%b: by binary;
%x: by hexadecimal;
%o: By octal;
$f: By floating point

/*
$var = 10;
printf(&#39;整型：%d<br>&#39;, $var);
printf(&#39;浮点型：%.2f<br>&#39;, $var); // 保留两位小数
printf(&#39;字符串：%s<br>&#39;, $var);
printf(&#39;二进制：%b<br>&#39;, $var);
printf(&#39;八进制：%o<br>&#39;, $var);
printf(&#39;十六进制：%x<br>&#39;, $var);
 
// 打印结果
/*
整型：10
浮点型：10.00
字符串：10
二进制：1010
八进制：12
十六进制：a
*/

sprintf

sprintf cannot directly output the variable value, but directly The value is read into the specified variable:

$ret = sprintf('%.2f', $var);
echo "结果：{$ret}<br>";

This function is used to format variable output is very useful and used a lot!

print_r

print_r This function is used to output an array, with one or two. If parameter two is set to YES, the expression information will not be output, but will return directly:

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

$arr = array('name' => '标哥的技术博客', 'site' => 'www.huangyibiao.com');
print_r($arr);
echo &#39;<br>&#39;;
 
// 参数二设置为true则不会打印，而是直接返回
$arr1 = print_r($arr, true);
echo "{$arr1}<br>";

var_dump

var_dump This function is used the most during debugging, right? For outputting the content, type, and string content of variables, it is often used for debugging in development:

// 当打印的是字符串，其中有对象时，打印出来是：
// string(20) "var_dump：Array
var_dump(&#39;var_dump：&#39; . $arr . &#39;<br>&#39;);
 
// 当只有对象本身时，打印出来如下：
// " array(2) { ["name"]=> string(21) "标哥的技术博客" ["site"]=> string(19) "www.huangyibiao.com" }
var_dump($arr);

die

#die function is also widely used. , during the debugging process, the following execution is often interrupted. It will output the content first, and then exit the program or not output the content:

if (!isset($type)) {
 die(&#39;I am die!<br>&#39;);
}

Summary:

The above functions can print object values, system function values ​​and array contents;
echo, print, and printf can print variable contents, but cannot display arrays and system super variable arrays;
print_r and var_dump Not only can you print arrays and scalar variables, but you can also print the contents of objects;
The var_dump statement can not only print the contents of variables and arrays, but also display the contents of Boolean variables and resources (resource);
The var_export function returns structural information about the variables passed to the function. It is similar to the var_dump() function, except that the content returned is legalphp code.

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