php数组练习十六道题

<?php
/**
 * 1、写函数创建长度为10的数组。数组中的元素为递增的奇数。首项为1。
 */
$ary = range(1, 10);
//Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [8] => 9 [9] => 10 ) 
print_r($ary);

/**
 * 2、创建长度为10的数组，数组中的元素为递增的等比数，比值为3。首项为1
 */
function myfun($n){
	return pow(3, $n-1);
}
$ary = range(1, 10);
$result = array_map(‘myfun‘,$ary);
echo ‘<br>‘;
//Array ( [0] => 1 [1] => 3 [2] => 9 [3] => 27 [4] => 81 [5] => 243 [6] => 729 [7] => 2187 [8] => 6561 [9] => 19683 ) 
print_r($result);

/**
 * 3、求数组中最大数所在的下标；
 * $arr = array(1,5,67,8,4,3,45,6,887,2);
 */
$arr = array(1,5,67,8,4,3,45,6,887,2);
$max = $arr[0];//假设第一个数是最大的
$index = 0;//记录最大数的key值，即下标
foreach ($arr AS $key=>$val) {
	if ($max < $val) {
		$max = $val;
		$index = $key;
	}
}
//最大数是：887，其下标是：8
echo ‘<br>最大数是：‘.$max . ‘，其下标是：‘ . $index;
/* $mval = max($arr);
echo ‘<br>‘;
print_r(array_search($mval, $arr)); */

/**
 * 4、创建一个长度为10的数组，数组中的元素满足斐波拉齐数列的规律；
 */
$arr = array(1,1);
for ($i=2; $i<10; $i++) {
	$arr[] = $arr[$i-1]+$arr[$i-2];
}
echo ‘<br>‘;
//Array ( [0] => 1 [1] => 1 [2] => 2 [3] => 3 [4] => 5 [5] => 8 [6] => 13 [7] => 21 [8] => 34 [9] => 55 ) 
print_r($arr);

/**
 * 5、计算数组中最大数和最小数的差；
 */
$arr = array(1,5,67,8,4,3,45,6,887,2);
/*系统函数简单实现
 * 
$minv = min($arr);
$maxv = max($arr);
echo ‘<br>‘;
echo ‘最大数是：‘ . $maxv .‘,最小数是：‘.$minv.‘，差是：‘.($maxv-$minv);
 */

/*不使用系统函数实现*/
$max = $arr[0];//假设第一个数是最大的
$min = $arr[0];//假设第一个数也是最小的
foreach ($arr AS $key=>$val) {
	if ($max < $val) {
		$max = $val;
	} elseif ($min > $val) {
		$min = $val;
	}
}
echo ‘<br>‘;
//最大数是：887,最小数是：1，差是：886
echo ‘最大数是：‘ . $max .‘,最小数是：‘.$min.‘，差是：‘.($max-$min);

/**
 * 6、写一个方法，将一个长度超过10的数组最后5项直接截取，不改变顺序直接变为前5项，
 * 如{1,2,3,4,5,6,7,8,9,10,11,12}在经过方法后变为：{8,9,10,11,12,1,2,3,4,5,6,7}
 */
function arrayHandel(&$ary, $count = 5) {
	if (!(is_array($ary) && count($ary)>10 && count($ary)>$count)) {
		return false;
	}
	$len = count($ary);
	while ($count>0) {
		$i = $len-1;
		$count--;
		array_unshift($ary, $ary[$i]);
		array_pop($ary);
	}
}
$array = array(1,2,3,4,5,6,7,8,9,10,11,12,13);
echo ‘<br>‘;
arrayHandel($array);
//Array ( [0] => 9 [1] => 10 [2] => 11 [3] => 12 [4] => 13 [5] => 1 [6] => 2 [7] => 3 [8] => 4 [9] => 5 [10] => 6 [11] => 7 [12] => 8 ) 
print_r($array);

/**
 * 
 * 7、将两个数组连接成一个新数组；
 * array_combine($keys, $values) 一个作键，一个作值，但是两个数组个数必须一致，不然会返回false
 * array_merge($array1)  覆盖相同的键名
 * array_merge_recursive($array1) 不覆盖相同键名，组成以键名组成的数组集合
 * 
 */
$arr1 = array(‘a‘=>123,‘b‘=>1234);
$arr2 = array(‘os‘=>‘linux‘,‘db‘=>‘mysql‘,‘language‘=>‘php‘,‘server‘=>‘nginx‘,‘b‘=>1256);
echo ‘<br>‘;
//Array ( [a] => 123 [b] => 1234 [os] => linux [db] => mysql [language] => php [server] => nginx ) 
print_r($arr1+$arr2);//$arr1会覆盖$arr2中相同键值,运算是从右至左，所以左边的覆盖右边
echo ‘<br>‘;
//boolean false
var_dump(array_combine($arr1,$arr2));//boolean false
echo ‘<br>‘;
//Array ( [a] => 123 [b] => 1256 [os] => linux [db] => mysql [language] => php [server] => nginx ) 
print_r(array_merge($arr1,$arr2));//$arr1和$arr2中的相同的元素被后一个$arr2的覆盖
echo ‘<br>‘;
//Array ( [a] => 123 [b] => Array ( [0] => 1234 [1] => 1256 ) [os] => linux [db] => mysql [language] => php [server] => nginx )
print_r(array_merge_recursive($arr1,$arr2));

/**
 * 数组逆序（不能直接使用rsort函数，不能生成新数组）；
 */
$ary = array(‘apple‘,‘juice‘,‘orange‘,‘85‘,‘0‘,‘app‘,‘1‘,‘2‘,‘5‘,‘z‘);
/* rsort($ary);
echo ‘<br>‘;
print_r($ary); */
for ($i=0;$i<count($ary);$i++){
	for ($j=$i+1;$j<count($ary);$j++){
		if($ary[$i]<$ary[$j]){
			$temp = $ary[$i];
			$ary[$i] = $ary[$j];
			$ary[$j] = $temp;
		}
	}
}
echo ‘<br>‘;
//Array ( [0] => z [1] => orange [2] => juice [3] => apple [4] => app [5] => 85 [6] => 5 [7] => 2 [8] => 1 [9] => 0 ) 
print_r($ary);


/**
 * 9、在长度为10的升序有序数组中插入一个数字，组成新数组，保证数组顺序（不能直接使用sort）
 */
$arr = range(1, 40, 2);
function insertAry($ary, $val) {
	$endAry = array();
	$len = count($ary);
	$index = 0;
	if ($ary[$len-1] < $val) {//若插入数比数组中任意数大
		$ary[] = $val;
		$endAry = $ary;
		return $endAry; 
	}
	while ($index<$len) {
		
		if ($ary[$index]>=$val){
			$endAry[$index++] = $val;
			for($i = $index;$i<$len+1;$i++){
				$endAry[$i] = $ary[$i-1]; 
			}
			break;
		} else {
			$endAry[$index] = $ary[$index];
		}
		$index++;
	}
	
	return $endAry;
}
echo ‘<br>‘;
//Array ( [0] => 1 [1] => 3 [2] => 5 [3] => 7 [4] => 9 [5] => 11 [6] => 13 [7] => 15 [8] => 17 [9] => 19 [10] => 21 [11] => 23 [12] => 25 
//[13] => 27 [14] => 29 [15] => 31 [16] => 33 [17] => 35 [18] => 37 [19] => 39 [20] => 88 ) 
print_r(insertAry($arr,88));



/**
 * 10、将一个无序数组排列成升序数组；（冒泡排序）
 */

$arr = array(888,-9,1,11,5,67,8,4,3,45,6,887,2);
$len = count($arr);

for ($i=0; $i<$len; $i++) {
	for ($j=$len-1; $j>$i; $j--) {
		if ($arr[$j]<$arr[$j-1]) {
			$temp = $arr[$j];
			$arr[$j] = $arr[$j-1];
			$arr[$j-1] = $temp;
		}
	}
}
echo ‘<br>‘;
//Array ( [0] => -9 [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 [6] => 6 [7] => 8 [8] => 11 [9] => 45 [10] => 67 [11] => 887 [12] => 888 )
print_r($arr);

/*********选择排序************/
$arr = array(888,-9,1,11,5,67,8,4,3,45,6,887,2);
for ($i=0; $i<$len; $i++) {
	for ($j=$i+1; $j<$len; $j++) {
		if ($arr[$j]<$arr[$i]) {
			$temp = $arr[$j];
			$arr[$j] = $arr[$i];
			$arr[$i] = $temp;
		}
	}

}
echo ‘<br>‘;
//Array ( [0] => -9 [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 [6] => 6 [7] => 8 [8] => 11 [9] => 45 [10] => 67 [11] => 887 [12] => 888 )
print_r($arr);



/**
 * 11、对有序数组进行洗牌操作；（不能直接使用shuffle函数）
 */
$arr = range(1, 40, 2);
echo ‘<br>‘;
echo ‘<br>$arr打乱前：‘;
//$arr打乱前：Array ( [0] => 1 [1] => 3 [2] => 5 [3] => 7 [4] => 9 [5] => 11 [6] => 13 [7] => 15 [8] => 17 [9] => 19 [10] => 21 [11] => 23 
//[12] => 25 [13] => 27 [14] => 29 [15] => 31 [16] => 33 [17] => 35 [18] => 37 [19] => 39 ) 
print_r($arr);
function shuffleDemo($arr) {
	$resultAry = array();
	$len = count($arr);
	while ($len>0) {
		$index = rand(0, $len-1);
		$resultAry[] = $arr[$index];
		array_splice($arr, $index,1);
		$len--;
	}
	return $resultAry;
}
echo ‘<br>‘;
echo ‘<br>$arr打乱后：‘;
//$arr打乱后：Array ( [0] => 3 [1] => 33 [2] => 11 [3] => 15 [4] => 5 [5] => 39 [6] => 1 [7] => 25 [8] => 35 [9] => 29 [10] => 13 [11] => 27 
//[12] => 23 [13] => 7 [14] => 37 [15] => 19 [16] => 9 [17] => 17 [18] => 31 [19] => 21 )
print_r(shuffleDemo($arr));



/**
 * 12、删除数组中指定位置的元素；(参考unset函数)
 */
function deleteAryElement(&$arr, $index){
	if (!(is_array($arr) && count($arr)>$index)) {
		return false;
	}
	unset($arr[$index]);
}
$arr = array(888,-9,1,11,5,67,8,4,3,45,6,887,2);
deleteAryElement($arr,2);
echo ‘<br>‘;
//Array ( [0] => 888 [1] => -9 [3] => 11 [4] => 5 [5] => 67 [6] => 8 [7] => 4 [8] => 3 [9] => 45 [10] => 6 [11] => 887 [12] => 2 ) 
print_r($arr);



/**
 * 13、将数组中素数删除组成新数组
 */
function filtFun($val) {//自定义过滤素数函数
	$flag = true;//判断是否是素数
	if (is_int($val)) {
		if ($val<=0) {
			$flag = false;
		}
		for ($i=$val-1;$i>1;$i--) {
			if ($val%$i==0) {
				$flag = false;
				break;
			}
		}
	} else {
		$flag = false;
	}
	return !$flag;
}
$arr = array(888,-9,1,11,5,67,8,4,3,45,6,887,2,‘a‘);
$rary = array_filter($arr, ‘filtFun‘);
echo ‘<br>‘;
//Array ( [0] => 888 [1] => -9 [6] => 8 [7] => 4 [9] => 45 [10] => 6 [13] => a )
print_r($rary);




/**
 * 14、写函数检查数组中是否存在某个元素（不能直接使用in_array）
 */
function exsitEle($arr, $value) {
	if (!(is_array($arr) && count($arr)>0)) {
		return false;
	}
	foreach ($arr AS $key=>$val) {
		if ($val==$value) {
			return true;
		}
	}
	return false;
}
$arr = array(888,-9,1,11,5,67,8,4,3,45,6,887,2,‘a‘,array(‘a‘=>14,‘b‘=>48));
//boolean true
var_dump(exsitEle($arr, array(‘a‘=>14,‘b‘=>48)));


/**
 * 15、写函数，向数组最后追加一个元素（不能直接使用array_push）
 */
$arr = array(888,-9,1,11,5,67,8,4,3,45,6,887,2,‘a‘,array(‘a‘=>14,‘b‘=>48));
$arr[] = ‘abcd‘;
echo ‘<br>‘;
//Array ( [0] => 888 [1] => -9 [2] => 1 [3] => 11 [4] => 5 [5] => 67 [6] => 8 [7] => 4 [8] => 3 [9] => 45 [10] => 6 
//[11] => 887 [12] => 2 [13] => a [14] => Array ( [a] => 14 [b] => 48 ) [15] => abcd )
print_r($arr);



/**
 * 16、写函数，求数组中所有元素之和（不能直接使用array_sum）
 */
$arr = array(888,-9,1,11,5,67,8,4,3,45,6,-102);
function countAry($arr) {
	if (!(is_array($arr) && count($arr)>0)) {
		return false;
	}
	$sum = 0;
	foreach ($arr AS $key=>$val) {
		$sum += $val;
	}
	return $sum;
}
echo ‘<br>‘;
//927
print_r(countAry($arr));