PHP basic array

$arr = array("a","b","c"); $arr1 = array("a"=>1,"b"=>2,5,10=>100); //关联数组 $arr2 = array(); $arr2[] = "15"; $arr2[] = 15; $arr3[] =100; $arr3[] =10; $arr3[] ='中国梦'; echo $arr3[0];

// 求一个一维数组的平均值 $a = array(1,11,12,13,100); $n =count($a); $sum =0; for ($i=0; $i <$n ; $i++) { $sum+=$a[$i]; } echo "一维数组的平均值是".$sum/$n."
"; // 求一个二维数组的平均值 $a1 = array( array(10,11,100), array(10,101,100), array(100,300,100,400), ); $len = count($a1); $sum = 0; $c = 0; for ($i=0; $i < $len; $i++) { $tempconut = count($a1[$i]); for ($k=0; $k < $tempconut; $k++) { $sum += $a1[$i][$k]; $c++; } } echo "二维数组的平均值为".$sum/$c."
"; // 求一个一维数组的最大值 $a3 = array(10,100,1,300); $count = count($a3); $max = $a3[0] ; for ($i=0; $i < $count ; $i++) { if($max < $a3[$i]){ $max = $a3[$i]; } } echo "一维数组的最大值是".$max."
"; // 求一个二维数组的最大值 $a4 = array( array(100,0,10,999), array(100000000000000,100,10,9999), array(10,55,10000,999999999), ); $max = $a4[0][0]; for ($i=0; $i < count($a4); $i++) { for ($k=0; $k < count($a4[$i]) ; $k++) { if($max < $a4[$i][$k]){ $max = $a4[$i][$k]; } } } echo "二维数组的最大值是".$max."
"; //交换一维数组的最大值和最小值 $arr5 = array(100,1,999,1024,888); $max_index = -1; $min_index = -1; $max = $arr5[0]; $min = $arr5[0]; for ($i=0; $i < count($arr5); $i++) { if($max < $arr5[$i]){ $max_index = $i;//最大值 $max = $arr5[$i]; } if($min > $arr5[$i]){ $min_index = $i;//最小值 $min = $arr5[$i]; } } $temp = $arr5[$max_index]; $arr5[$max_index] = $arr5[$min_index]; $arr5[$min_index] = $temp; echo "最大值索引是".$max_index."最小值索引是".$min_index."
"; echo "一维数组最大值和最小值交换后的结果为".implode(" ",$arr5)."
";

$arr = array(1,100,35); foreach ($arr as $key => $value) { echo $value; }

//数组指针操作 $arr = array(10,200,500); do{ echo current($arr)."
"; }while(next($arr)); //指针默认在第一个元素处

$arr2 = array(100,88,1989,10,30); foreach ($arr2 as $key => $value) { } $key = key($arr2); $value = current($arr2); //遍历之后指针的位置 var_dump($key); //NULL var_dump($value); //false

$arr3 = array(1=>100,"aa"=>900,"中国梦"); for ($i=0; $i
         "; }< pre>
          

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