Program:

unsigned long closestIntSameBit(unsigned int x ) { 
    for (int i =0 ; i <63; i++) {        
        if(( (x >> i) &  1 ) != ((x >> (i + 1 )) &  1 )) { 
            x =  x ^ (1UL << i ) + (1UL << (i + 1 ) );
            return x; 
        }
    } 

}