


Summary of some examples of commonly used output functions in PHP
echo(); "输出内容";
可以同时输出多个字符串,可以多个参数,并不需要圆括号 ,无返回值。
print(); 有返回值1,0切只能包含一个参数
只可以同时输出一个字符串,一个参数, 需要圆括号,有返回值, 当其执行失败时返 flase。
print 的用法和 C语言很像,所以会对输出内容里的 % 做特殊解释。
$a=print(‘hi'); echo $a; //—————————- hi 1 //1 是 $a 的值。 //—————————–
die(); 一般用于数据库连接的判断,一旦执行die()后面的内容将不执行
die(); // 和 exit() 区别。
有两个功能:先输出内容,然后退出程序。(常用在链接服务器,数据库)
mysql_connect(“locahost”,”root”,”root”) or die(”链接服务器失败!“);
printf(); 与C语言的用法一样,可以格式化输出
printf(); //f 指 format 格式化
printf(“参数 1″,参数 2) :参数 1= 按什么格式输出;参数 2= 输出的变量。
(% s: 按字符串; %d: 按整型整型 ; %b: 按二进制; % x: 按 16 进制; %X:按16 进制大写输出; %o: 按八进制; % f: 按浮点型 )
函数,返回输出字符个数,把文字格式化以后输出,如:
printf (“$%01.2f” , 43.2); //$43.20
$ 表示填充的字符
0 表示位数不够在不影响原值的情况下补
1 表示输出的总宽度
2 表示小数位数 ,有四舍五入
%f 是表示显示为一个浮点数
格式化命令及说明:
%% 印出百分比符号,不转换。
%b 整数转成二进位。
%c 整数转成对应的 ASCII 字符。
%d 整数转成十进位。
%f 倍精确度数字转成浮点数。
%o 整数转成八进位。
%s 整数转成字符串。
%x 整数转成小写十六进位。
%X 整数转成大写十六进位。
<?php $num=100.001; printf(“%d”,$num); //100 printf(“%s”,$num); //100.001 printf(“%s—%d—%b—%x—%o—%f”,$num,$num,$num,$num,$num,$num) //100.001—100—1100100—64—144—1001.00100 printf(“%.2f”,$num); //100.00 ( 小数点保留 2 位) printf(“%.1f”,$num); //100.0 ( 小数点保留 1 位) printf(“%`#10s”,$num); //#10s printf(“%#10s”,$num); //10s ?>
sprintf; 把输出内容存放在变量中
此并不能直接输出,先赋给一个变量,然后再输出变量。
<?php $num=100.001; $a=sprintf(“%d”,$num); echo $a; //100 ?>
print_r(); 用于输出数组
功能:只用于输出数组。
$a = array (1, 2, array (“a”, “b”, “c”)); print_r ($a);
返回:
Array ( [0] => 1 [1] => 2 [2] => Array ( [0] => a [1] => b [2] => c ) )
var_dump(); 可以输出任何内容
输出变量的容,类型或字符串的内容,类型,长度。常用来调试。
<?php $a=100; var_dump($a); //int(100) $a=100.356; var_dump($a); //float(100.356) ?>
var_export ();
返回关于传递给该函数的变量的结构信息,它和var_dump()类似,不同的是其返回的表 示是合法的 PHP 代码。
您可以通过将函数的第二个参数设置为TRUE ,从而返回变量的值。
<?php $a = array (1, 2, array (“a”, “b”, “c”)); var_export ($a); /* 输出: array ( 0 => 1, 1 => 2, 2 => array ( 0 => ‘a', 1 => ‘b', 2 => ‘c', ), ) */ $b = 3.1; $v = var_export($b, TRUE); echo $v; /* 输出: 3.1 */ ?>
简化用法:
<?php $color = "red"; ?> <p>Roses are <?=$color?></p>
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