函数模板T max(T a, T b, T c),使之实现对任何类型数，能从三个数中求出最大数返回。设计各种类型数据(char，short，long，float，double)调用此函数模板。-function template T max (T a, b T, T c), to enable it to achieve any of several types, a few were from the three sought to return to the greatest number. Design data types (char, short, long, float, double) calling this function template.