c++ - for循环中的逗号

Question

为什么下面一行会产生错误？

for(int i = 0, int pos = 0, int next_pos = 0; i < 3; i++, pos = next_pos + 1) {
  // …
}

error: expected unqualified-id before ‘int’
error: ‘pos’ was not declared in this scope
error: ‘next_pos’ was not declared in this scope

编译器是 g++。

Answer 1

每个语句只能有一种类型的声明，所以你只需要一个 int:

for(int i = 0, pos = 0, next_pos = 0; i < 3; i++, pos = next_pos + 1)