量变产生质变

剑指Offer：表示数值的字符串 LeetCode链接 bool isNumber(string s) { int begin = 0; bool abool = false; while (s[begin] == ' ') { begin++; } if (s[begin] == '+' || s[begin] == '-') begin++; while (isdigit(s[begin])) { begin++; abool = true; } if (s[b