1、数组初始化
a[5] = {1}; //1,0,0,0,0
a[5] = {0}; //0,0,0,0,0
a[3][3] = {1}; //1,0,0;0,0,0;0,0,0
a[3][3] = {0}; //0,0,0;0,0,0;0,0,0
