the difference b/w 1==n&1 and n&1==1 , n is an unsigned int

问题

this is a program problem from leetcode.it gives an unsigned int n，ask you to return the numbers of bit '1';

int hammingWeight(uint32_t n) {
int num=0;
for(;n!=0;n=n>>1)
{
    if(n&1==1)
    {
        num++;
    }
}
return num;
}

this works perfectly,but

int hammingWeight(uint32_t n) {
int num=0;
for(;n!=0;n=n>>1)
{
    if(1==n&1)
    {
        num++;
    }
}
return num;
}

this one cant work sometimes! i guess something is wrong when 1 calculate with an uint32_t,but i cant understand this clearly.

回答1:

== has higher precedence than &. Thus,

• n&1==1 is n & (1==1), while
• 1==n&1 is (1==n) & 1.

来源：https://stackoverflow.com/questions/31490996/the-difference-b-w-1-n1-and-n1-1-n-is-an-unsigned-int