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A number n is a power of 4 if following conditions are met.
a) There is only one bit set in the binary representation of n (or n is a power of 2) b) The count of zero bits before the (only) set bit is even.For example: 16 (10000) is power of 4 because there is only one bit set and count of 0s before the set bit is 4 which is even.
bool isPowerOfFour(unsigned int n){ int count = 0; /*Check if there is only one bit set in n*/ if ( n && !(n&(n-1)) ) { /* count 0 bits before set bit */ while(n > 1) { n >>= 1; count += 1; } /*If count is even then return true else false*/ return (count%2 == 0)? 1 :0; } /* If there are more than 1 bit set then n is not a power of 4*/ return 0;} 转载地址：http://lexti.baihongyu.com/