【转】PHP：echo、print、print_r、sprintf、var_dump其间的区别-PHP Tutorial-php.cn

【转】PHP：echo、print、print_r、sprintf、var_dump之间的区别

- echo
是命令，不能返回值。echo后面可以跟很多个参数，之间用分号隔开，如：

<span style="color: #b1b100;">echo</span> <span style="color: #000088;">$myvar1</span><span style="color: #339933;">;</span><span style="color: #b1b100;">echo</span> <span style="color: #cc66cc;">1</span><span style="color: #339933;">,</span><span style="color: #cc66cc;">2</span><span style="color: #339933;">,</span><span style="color: #000088;">$myvar</span><span style="color: #339933;">,</span><span style="color: #0000ff;">"<b>bold</b>"</span><span style="color: #339933;">;</span>

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- print
是函数，可以返回一个值，只能有一个参数。

- printf
函数，把文字格式化以后输出，如：

<span style="color: #000088;">$name</span><span style="color: #339933;">=</span><span style="color: #0000ff;">"hunte"</span><span style="color: #339933;">;</span><span style="color: #000088;">$age</span><span style="color: #339933;">=</span><span style="color: #cc66cc;">25</span><span style="color: #339933;">;</span><span style="color: #990000;">printf</span><span style="color: #009900;">(</span><span style="color: #0000ff;">"my name is <span style="color: #009933; font-weight: bold;">%s</span>, age <span style="color: #009933; font-weight: bold;">%d</span>"</span><span style="color: #339933;">,</span> <span style="color: #000088;">$name</span><span style="color: #339933;">,</span> <span style="color: #000088;">$age</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>

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- sprintf
跟printf相似，但不打印，而是返回格式化后的文字，其他的与printf一样。

- print_r
print_r通常用于打印变量的相关信息，通常在调试中使用。

<span style="color: #990000;">print_r</span><span style="color: #009900;">(</span><span style="color: #009900; font-weight: bold;">true</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>           <span style="color: #666666;">//输出1</span><span style="color: #990000;">print_r</span><span style="color: #009900;">(</span><span style="color: #009900; font-weight: bold;">false</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>          <span style="color: #666666;">//没有输出</span><span style="color: #990000;">print_r</span><span style="color: #009900;">(</span><span style="color: #009900; font-weight: bold;">null</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>          <span style="color: #666666;">//没有输出</span>

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- var_dump
var_dump此函数显示关于一个或多个表达式的结构信息，包括表达式的类型与值。

<span style="color: #990000;">var_dump</span><span style="color: #009900;">(</span><span style="color: #009900; font-weight: bold;">true</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span> <span style="color: #666666;">//输出 bool(true)</span><span style="color: #990000;">var_dump</span><span style="color: #009900;">(</span><span style="color: #009900; font-weight: bold;">false</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>   <span style="color: #666666;">// bool(false)</span><span style="color: #990000;">var_dump</span><span style="color: #009900;">(</span><span style="color: #009900; font-weight: bold;">null</span><span style="color: #009900;">)</span><span style="color: #339933;">;</span>   <span style="color: #666666;">// bool(null)</span>

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var_dump()和print_r()的区别：
var_dump返回表达式的类型与值而print_r仅返回结果，相比调试代码使用var_dump更便于阅读。

Related labels：

dump echo print printf var

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