设有两个2*3矩阵a,b，重载运算符+，用于两个矩阵的加法运算，如c=a+b，设c也为2*3的矩阵。重载<< 和>>，用于输入输出矩阵。-There are two 2* 3 matrix a, b, overloaded operator+ for addition operation of two matrices, such as c = a+ b, c set for 2* 3 matrix. Overloading < < and> > f