将数列a=1,2,3,4,5,6,7...变成4,4,4,4,8,8,8,8,12,12...一个很巧妙的办法((a+3)>>2)<<2,当然不用位运算就可以用(a+3)-(a+3)%4

//  模4编号的实现 
#include <stdio.h>
#include <stdlib.h>
int main()
{/*for(int i=1;i<=100;i++){//printf("%d %d   ",i,((i+3)>>2)<<2);printf("%d %d   ",i,3-(i+3)%4);if(i%4==0)printf("\n");}*/int width=10,height=8;printf("\t\t顺序编号\n");for(int i=0;i<height;i++){for(int j=0;j<width;j++)printf("%3d ",width*i+j);//实际像素编号printf("\n");}printf("\n");printf("\t\t模4编号\n");for(int i=0;i<height;i++){for(int j=0;j<width;j++)printf("%3d ",width*i+j+(3-(width+3)%4)*i);//模4像素编号 printf("\n");}printf("\n");system("pause");return 0;
}