foreach与正常for循环效率之间解析-tutorial php-php.cn

可以看出，循环ArrayList时，普通for循环比foreach循环花费的时间要少一点；

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'>循环LinkList时，普通for循环比foreach循环花费的时间要多很多。

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'>当我将循环次数提升到一百万次的时候，循环ArrayList，普通for循环还是比foreach要快一点；

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'>但是普通for循环在循环LinkList时，程序直接卡死。

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'> 结论： 需要 循环数组结构 的数据 使用时，建议普通for循环 ，因为for循环采用下标访问，对于数组结构的数据来说，采用下标访问比较好。

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'> 需要 循环链表结构 的数据时， 一定不要使用普通for循环 ，这种做法很糟糕，数据量大的时候有可能会导致系统崩溃。

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'> 原因：foreach使用的是迭代器。

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'> 相关推荐：

<p style='font-family: "Microsoft YaHei", 微软雅黑, " WenQuanYi Micro Hei", "Helvetica Neue", Arial, "Hiragino Sans GB", "WenQuanYi Micro Hei", "Droid Sans Mono", "Droid Sans Fallback", sans-serif; margin: 0px 0px 0.3em; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; line-height: 20px; text-indent: 2em; text-transform: none; white-space: normal; word-spacing: 0px; background-color: rgb(255, 255, 255); text-align: left;'> php foreach与for语句用法区别介绍_PHP教程