fig04_06.pl

来自「PERL语言资料 可以用于PERL程序设计」· PL 代码 · 共 44 行

#!/usr/bin/perl
# Fig. 4.6: fig04_06.pl
# Create an array by referring to nonexistent elements.

# Create @array with one element by referring to 
# nonexistent element 0.
$array[ 0 ] = "happy";
print "@array\n";

# Add more elements to @array by referring to 
# nonexistent element 3. There are now 4 elements
# in the array. Elements 1 and 2 have undefined values.
$array[ 3 ] = "birthday";
print "@array\n\n";

# Loop through the array and replace every undefined
# value with an actual value.
for ( $i = 0; $i < 4; ++$i ) {

   # if the element is not defined, assign it a value
   if ( ! defined( $array[ $i ] ) ) {
      $array[ $i ] = "happy";
   }
}

print "@array\n";
print @array, "\n";

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