PHP / MySQLPosted on 2023-04-19
摘要 : 加号+操作符：键名重叠时以前者为准。
array_merge() 函数：关联索引部分键名重叠时以后者为准，数字索引部分优先添加前再添加后者。
❱ 加号+操作符：键名重叠时以前者为准
❱ 2个数组都是数字索引，重叠部分以前者为准
$a = array('a','b','c');
$b = array('A1','B2','C3','D4');
$c = $a + $b;
print_r($c);
// 结果：
Array ( [0] => a [1] => b [2] => c [3] => D4 )
❱ 2个数组都是关联索引，重叠部分以前者为准
$a = array('a0'=>'a','b'=>'b','c'=>'c');
$b = array('A'=>'A1','B'=>'B2','C'=>'C3','a0'=>'ax');
$c = $a + $b;
print_r($c);
// 结果
Array ( [a0] => a [b] => b [c] => c [A] => A1 [B] => B2 [C] => C3 )
❱ 2个数组混合数字索引、关联索引，重叠部分以前者为准
$a = array('a0'=>'a','b','c');
$b = array('A'=>'A1','B2','C3','a0'=>'ax');
$c = $a + $b;
print_r($c);
// 结果
//Array ( [a0] => a [0] => b [1] => c [A] => A1 )
❱ array_merge() 函数：键名重叠时以后者为准
❱ 2个数组都是数字索引，自动在前者尾部添加后者的内容
$a = array('a','b','c');
$b = array('A1','B2','C3','D4');
$c = array_merge( $a , $b);
print_r($c);
// 结果
//Array ( [0] => a [1] => b [2] => c [3] => A1 [4] => B2 [5] => C3 [6] => D4 )
❱ 2个数组混合数字索引、关联索引，关联索引部分键名重叠时以后者为准，数字索引部分优先添加前再添加后者
$a = array('a0'=>'a','b','c');
$b = array('A'=>'A1','B2','C3','a0'=>'ax');
$c = array_merge( $a , $b);
print_r($c);
// 结果
//Array ( [a0] => ax [0] => b [1] => c [A] => A1 [2] => B2 [3] => C3 )