转载自https://blog.csdn.net/kenden23/article/details/18696083
class Solution {
public:
bool isNumber(const char *s) {
enum InputType {
INVALID, // 0 Include: Alphas, '(', '&' ans so on
SPACE, // 1
SIGN, // 2 '+','-'
DIGIT, // 3 numbers
DOT, // 4 '.'
EXPONENT, // 5 'e' 'E'
};
int transTable[][6] = {
//0INVA,1SPA,2SIG,3DI,4DO,5E
-1, 0, 3, 1, 2, -1,//0初始无输入或者只有space的状态
-1, 8, -1, 1, 4, 5,//1输入了数字之后的状态
-1, -1, -1, 4, -1, -1,//2前面无数字，只输入了Dot的状态
-1, -1, -1, 1, 2, -1,//3输入了符号状态
-1, 8, -1, 4, -1, 5,//4前面有数字和有dot的状态
-1, -1, 6, 7, -1, -1,//5'e' or 'E'输入后的状态
-1, -1, -1, 7, -1, -1,//6输入e之后输入Sign的状态
-1, 8, -1, 7, -1, -1,//7输入e后输入数字的状态
-1, 8, -1, -1, -1, -1,//8前面有有效数输入之后，输入space的状态
};
int state = 0;
while (*s)
{
InputType input = INVALID;
if (*s == ' ') input = SPACE;
else if (*s == '+' || *s == '-') input = SIGN;
else if (isdigit(*s)) input = DIGIT;
else if (*s == '.') input = DOT;
else if (*s == 'e' || *s == 'E') input = EXPONENT;
state = transTable[state][input];
if (state == -1) return false;
++s;
}
return state == 1 || state == 4 || state == 7 || state == 8;
}
};| 访问量: 次
