C语言无符号数的识别程序

例如：下面几个数应该是符合规则的数：

             3，3.51，34E3,34.5E2,34.5E+2,34.5E-2

 要求：编写程序，输入一串字符，判断是不是一个无符号实数。

参考代码：

#include

void main()

{

    int states=0,error=0;

    char c;

    while(error==0 && (c=getchar())!='\\n')

    {

        switch(states)

        {case 0: 

         if(c>='0' && c<='9')

                states=1;

            else

                error=1;

            break;

         case 1:

         if(c>='0' && c<='9')

              states=1;   //这行可以省略

            else

              if(c=='.') states=2;

              else 

                if(c=='E' || c=='e') states=4;

                  else  

                    error=1;

            break;

         case 2:

         if(c>='0' && c<='9')

                states=3;

            else

                error=1;

            break;

         case 3:

         if(c>='0' && c<='9')

                states=3; //这行可以省略

            else

                if(c=='E' || c=='e') states=4;

                else  

                    error=1;

            break;

         case 4:

         if(c>='0' && c<='9')

                states=6;

            else

                if(c=='+' || c=='-') states=5;

                else  

                    error=1;

            break;

         case 5:

         if(c>='0' && c<='9')

                states=6;

            else

                error=1;

            break;

         case 6:

         if(c>='0' && c<='9')

                states=6;  //这行可以省略

            else

                error=1;

        }

    }

    if(error==0) printf("是无符号实数"); 

    else printf("不是无符号实数");

}