Output variables in PHP can use six language structures: echo(), print(), print_r(), var_dump(), printf() and sprintf(). The selection criteria are: echo() and print() for simple output; print_r() and var_dump() for output of complex data structures; printf() and sprintf() for formatted output.
Language structure for variable output in PHP
The following language structure can be used to output variables in PHP:
1. echo()
<code class="php">echo $variable;</code>
2. print()
<code class="php">print $variable;</code>
3. print_r()
In addition to outputting the value of the variable, print_r()
also outputs the type and structure of the variable, which is suitable for outputting complex data structures.
<code class="php">print_r($array);</code>
4. var_dump()
is similar to print_r()
, but more detailed. It outputs the complete information of the variable, including its type, Value and reference counting.
<code class="php">var_dump($variable);</code>
5. printf()
is used to format output and can specify output format and modifiers.
<code class="php">printf("变量的值是 %s", $variable);</code>
6. sprintf()
is similar to printf()
, but returns the formatted output as a string instead of Output directly to the screen.
<code class="php">$output = sprintf("变量的值是 %s", $variable);</code>
Guidelines for choosing language constructs:
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