数据结构中有关的逆置问题，vs2022代码运行问题？

Question

#include<iostream>
#define maxsize 100
void seqlistR1(int seqlist[], int length)
{
    int left = 0;
    int right = length - 1;
    for (left, right; left < right; left++, right--)
    {
        int temp = seqlist[left];
        seqlist[left] = seqlist[right];
        seqlist[right] = temp;
    }
    for (int a=0,int b=length-4; a <b; a++, b--)
    {
        int temp = seqlist[a];
        seqlist[a] = seqlist[b];
        seqlist[b] = temp;
    }
}
void Printf(int seqlist[],int length)
{
    for (int i = 0; i < length; i++)
    {
        std::cout << seqlist[i]<<" ";
    }
}
int main()
{
    int seqlist[maxsize] = { 1,2,3,4,5,6,7,8 };
    int length = 8;
    seqlistR1(seqlist, length);
    Printf(seqlist,length);
    return 0;
}

我想用上面这个代码去实现：将1 2 3 4 5 6 7 8，改为4 5 6 7 8 3 2 1
我在seqlistR1函数里面用了两个for循环，可是代码运行有问题。
报的错为
而当我把函数中的第二个循环单独写成一个函数时，代码且可以运行了。

另一个代码如下：

#include<iostream>
#define maxsize 100
void seqlistR1(int seqlist[], int length)
{
    int left = 0;
    int right = length - 1;
    for (left, right; left < right; left++, right--)
    {
        int temp = seqlist[left];
        seqlist[left] = seqlist[right];
        seqlist[right] = temp;
    }
}
void seqlistR2(int seqlist[], int length)
{
    int left = 0;
    int right = length - 4;
    for (left, right; left < right; left++, right--)
    {
        int temp = seqlist[left];
        seqlist[left] = seqlist[right];
        seqlist[right] = temp;
    }
}
void Printf(int seqlist[], int length)
{
    for (int i = 0; i < length; i++)
    {
        std::cout << seqlist[i] << " ";
    }
}
int main()
{
    int seqlist[maxsize] = { 1,2,3,4,5,6,7,8 };
    int length = 8;
    seqlistR1(seqlist, length);
    seqlistR2(seqlist, length);
    Printf(seqlist, length);
    return 0;
}

我想知道为什么会出现这种情况？