<?php
//n +(n+1)+...+(m-1)+m(n>0,m>n)
function sum($n,$m){
if($m<=$n){
return $n;
}
return sum($n,$m-1)+$m;
}
echo sum(1,100);
//执行流程如下
#sum(1,100)=>sum(1,99)+100=>sum(1,98)+99....=>sum(1,1)
//最终数据被替换完毕 故成了从1加到100
<?php
//n +(n+1)+...+(m-1)+m(n>0,m>n)
function sum($n,$m){
if($m<=$n){
return $n;
}
return sum($n,$m-1)+$m;
}
echo sum(1,100);
//执行流程如下
#sum(1,100)=>sum(1,99)+100=>sum(1,98)+99....=>sum(1,1)
//最终数据被替换完毕 故成了从1加到100