for语句的$i 和$sum变量必须在括号里面赋值呢？

Answer 1

The $i and $sum variables in the for statement must be assigned values ​​inside parentheses? -PHP Chinese website Q&A-Do the $i and $sum variables in the for statement have to be assigned within parentheses? -PHP Chinese website Q&A

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Answer 2

也可以在外面先赋值，放在循环内，代码会比较简洁一点！现在大部分都习惯了这样的写法！