前些时候做过的一份面试试题[7]

         //完成类似于vb的left函数的功能（返回字符串ssource的左ilength位的字符串）。

         console.writeline("please enter a string to treaded:");

         string s = console.readline();

         int i = 0;

         bool binputvalid = false;

         while(!binputvalid){

                   try{

                            console.writeline("please enter the length from left most:");

                            i = convert.toint32(console.readline());

                            if(i > s.length) throw new exception("");