A matrix is a rectangular array of numbers. A matrix with m rows and n columns is called an m × n matrix. The plural of matrix is matrices. A matrix with the same number of rows as columns is called equal if they have the same number of rows and the same number of columns and the corresponding entries in every position are equal
string is composed ofn(20) characters in an orderly sequence recorded as s:“c1C2C3…Cn” S is string name c123n is value is a character n is string length Such as,S=“ TSinghua University