Question

用php写出1+2+3+.....n怎么写

Answer 1

<?php
$n = 100; //自定义,一定要设个范围，不然就进入死循环了
$sum = 0;
for($i=1; $i <= $n; $i++){
$sum = $sum + $i;
if($i==1){
echo $i;
}else{
echo "+".$i;
}
}
echo "<br />".$sum;
?>

Answer 2

function myFunc($n) {
$m = 0;
for (;$n > 0 ; n--) {
$m += $n;
}
return $m;
}

//例子，调用传入100并输出
echo myFunc(100);
//------???????-----
function myFuncAdd($n) {
$m = '';
for ($i = 1;$i <= $n ; $i++) {
$m = $m . '+' . $i;
}
return $m;
}
//例子，调用传入100并输出
echo myFuncAdd(100);

Answer 3

<form name="form1" method="post" action="">
输入n的值:
<input name="bigN" type="text" id="bigN">
<p>
<input type="submit" name="Submit" value="提交">
</p>
</form>

<?php
$n = $_POST['bigN'];
$sum = 0;

for($i=1; $i <= $n; $i++)
{
$sum = $sum + $i;
}
echo "<br />".$sum;
?>

Answer 4

<?php
$item = 1;
$n = 10; //这个值你自己设置的N
$result = 0;
while($item<=$n)
{
$result = $result + $item;
$item++;
}
echo $result;
?>
这样就OK了

Answer 5

function fun($n) {
$num = 0;
for ($i = 0;$i <= $n ; $i++) {
$num += $i;
}
return $num;
}

//例子，调用传入100并输出
echo fun(100);