for loop is giving different result than +=

Question

I really do not understand what is happening here but:

when I do:

colorIndex += len - stopPos;
for(int m = 0; m < len - stopPos; m++)
{
    colorUniPos++;
}

it does not give me the same result as doing:

colorIndex += len - stopPos;
colorUniPos += len - stopPos;

I think it becomes off by one or something. Shouldn't both of these obtain the same result?

Thanks

Answer 1

如果len-stopPos <0，则不会产生相同的结果

Answer 2

如果len - stopPos是正值或零，这是正确的，但对于负值， colorUniPos只是保留其值，因为未执行循环。