PHP练习--用for循环打印空心菱形，for菱形
思路：1，写出代码打印实心的金字塔
2、修改代码，把金字塔抛空
3、修改代码，把金字塔倒转
4、修改倒转后的代码，把金字塔抛空
立即学习“PHP免费学习笔记（深入）”；
5、修改代码，把具体的数进行参数化
1、写出代码打印实心金字的金字塔：
<?<span>php
</span><span>//</span><span>$n=5;</span>
<span>for</span>(<span>$i</span>=1;<span>$i</span><=5;<span>$i</span>++<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=1;<span>$j</span><=5-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-1;<span>$k</span>++<span>){
</span><span>echo</span> "*"<span>;
}
</span><span>echo</span> "<br/>"<span>;
}
</span>?>
2、
2、改善代码，把金字塔抛空
<?<span>php
</span><span>//</span><span>$n=5;</span>
<span>for</span>(<span>$i</span>=1;<span>$i</span><=5;<span>$i</span>++<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=1;<span>$j</span><=5-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-1;<span>$k</span>++<span>){
</span><span>//</span><span>打印第一行后最后一行都打*连接</span>
<span>if</span>(<span>$i</span>==1 || <span>$i</span>==5<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>//</span><span>怎么打空格和*号的问题</span>
<span>if</span>(<span>$k</span>==1 || <span>$k</span>==2*<span>$i</span>-1<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>echo</span> " "<span>;
}
}
}
</span><span>echo</span> "<br/>"<span>;
}
</span>?>
3、修改代码，把金字塔倒转
<?<span>php
</span><span>//</span><span>$n=5;</span>
<span>for</span>(<span>$i</span>=1;<span>$i</span><=5;<span>$i</span>++<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=1;<span>$j</span><=5-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-1;<span>$k</span>++<span>){
</span><span>//</span><span>打印第一行后最后一行都打*连接</span>
<span>if</span>(<span>$i</span>==1 || <span>$i</span>==5<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>//</span><span>怎么打空格和*号的问题</span>
<span>if</span>(<span>$k</span>==1 || <span>$k</span>==2*<span>$i</span>-1<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>echo</span> " "<span>;
}
}
}
</span><span>echo</span> "<br/>"<span>;
}
</span><span>//</span><span>倒转</span>
<span>for</span>(<span>$i</span>=5;<span>$i</span>>=0;<span>$i</span>--<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=0;<span>$j</span><=5-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-3;<span>$k</span>++<span>){
</span><span>echo</span> "*"<span>;
}
</span><span>echo</span> "<br/>"<span>;
}
</span>?>
4、修改倒转后的代码，把金字塔抛空，并把中间的*号去掉 修改这里的代码（if($i==1 || $i==5){ //去掉$i==5 把中间抛空）
<?<span>php
</span><span>//</span><span>$n=5;</span>
<span>for</span>(<span>$i</span>=1;<span>$i</span><=5;<span>$i</span>++<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=1;<span>$j</span><=5-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-1;<span>$k</span>++<span>){
</span><span>//</span><span>打印第一行后最后一行都打*连接($i==1 || $i==5) </span>
<span>if</span>(<span>$i</span>==1){ <span>//</span><span>去掉$i==5 把中间抛空</span>
<span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>//</span><span>怎么打空格和*号的问题</span>
<span>if</span>(<span>$k</span>==1 || <span>$k</span>==2*<span>$i</span>-1<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>echo</span> " "<span>;
}
}
}
</span><span>echo</span> "<br/>"<span>;
}
</span><span>//</span><span>倒转 抛空</span>
<span>for</span>(<span>$i</span>=5;<span>$i</span>>=0;<span>$i</span>--<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=0;<span>$j</span><=5-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-3;<span>$k</span>++<span>){
</span><span>//</span><span>怎么打空格和*号的问题</span>
<span>if</span>(<span>$k</span>==2*<span>$i</span>-3 || <span>$k</span>==1<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>echo</span> " "<span>;
}
}
</span><span>echo</span> "<br/>"<span>;
}
</span>?>
5、修改代码，把具体的数进行参数化 ：把具体数字5改成$n=5代替，随后可以设置$n的值，可以任意放大和缩小
<?<span>php
</span><span>$n</span>=5<span>;
</span><span>for</span>(<span>$i</span>=1;<span>$i</span><=<span>$n</span>;<span>$i</span>++<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=1;<span>$j</span><=<span>$n</span>-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-1;<span>$k</span>++<span>){
</span><span>//</span><span>打印第一行后最后一行都打*连接($i==1 || $i==5) </span>
<span>if</span>(<span>$i</span>==1){ <span>//</span><span>去掉$i==5 把中间抛空</span>
<span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>//</span><span>怎么打空格和*号的问题</span>
<span>if</span>(<span>$k</span>==1 || <span>$k</span>==2*<span>$i</span>-1<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>echo</span> " "<span>;
}
}
}
</span><span>echo</span> "<br/>"<span>;
}
</span><span>//</span><span>倒转 抛空</span>
<span>for</span>(<span>$i</span>=<span>$n</span>;<span>$i</span>>=0;<span>$i</span>--<span>){
</span><span>//</span><span>打印空格</span>
<span>for</span>(<span>$j</span>=0;<span>$j</span><=<span>$n</span>-<span>$i</span>;<span>$j</span>++<span>){
</span><span>echo</span> " "<span>;
}
</span><span>//</span><span>打印*号</span>
<span>for</span>(<span>$k</span>=1;<span>$k</span><=2*<span>$i</span>-3;<span>$k</span>++<span>){
</span><span>//</span><span>怎么打空格和*号的问题</span>
<span>if</span>(<span>$k</span>==2*<span>$i</span>-3 || <span>$k</span>==1<span>){
</span><span>echo</span> "*"<span>;
}</span><span>else</span><span>{
</span><span>echo</span> " "<span>;
}
}
</span><span>echo</span> "<br/>"<span>;
}
</span>?>
效果图：
最后大功告成。顺便说说 ，其实编程不难，难就难在怎么样的思路，怎样去解决问题的方法。所以大家在编程的过程中善于思考。尽管花了半天的时间去想，但是最后想出来了，问题也得到解决，所以平时要多动脑动手去实践。我们的编程能力才能提高。只有实践了，东西才能被理解，知识点也掌握了。
