String to Integer (atoi)
来源:互联网 发布:mac能玩csgo吗 编辑:程序博客网 时间:2024/06/15 19:45
一、题目要求
Implement atoi to convert a string to an integer.
Requirements for atoi:
The function first discards as many whitespace characters as necessary until the first non-whitespace character is found. Then, starting from this character, takes an optional initial plus or minus sign followed by as many numerical digits as possible, and interprets them as a numerical value.
The string can contain additional characters after those that form the integral number, which are ignored and have no effect on the behavior of this function.
If the first sequence of non-whitespace characters in str is not a valid integral number, or if no such sequence exists because either str is empty or it contains only whitespace characters, no conversion is performed.
If no valid conversion could be performed, a zero value is returned. If the correct value is out of the range of representable values, INT_MAX (2147483647) or INT_MIN (-2147483648) is returned.
二、代码实现
int myAtoi(string str) { int result=0; if(str.empty()) return 0; //only '+' or '-' or whitespace for(auto tmp=0;tmp<str.size();tmp++) { if(str[tmp]==' ') str.erase(tmp--,1); else break; } bool sign=true; if(str.empty()) return 0; // if(str[0]=='+') str.erase(0,1); else if(str[0]=='-') {str.erase(0,1);sign=false; } int i,base=1,old; for(i=0;i<str.size();i++) {if(str[i]>='0' && str[i]<='9'){int tmp=str[i]-'0';old=result;result=tmp+result*10;if(old!=(result/10)){if(sign)return INT_MAX;elsereturn INT_MIN;}}elsebreak; } if(!sign) result=-result; return result; }
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- string to integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer(atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- String to Integer (atoi)
- 虚拟机安装CentOS 7系统(图文教程)
- 如何制件自由选区(笔记) wpf
- HDU1106 排序
- 2015071904 - 要有意识地磨练自己的意志
- shell脚本-批量添加或删除用户
- String to Integer (atoi)
- 八皇后问题
- 2015071905 - 你付出了什么?
- Palindrome Number
- Tomcat虚拟目录的配置
- 设计模式--职责链模式
- java常用类源代码探究(二):装箱类
- HDU1201 18岁生日
- 源代码控制管理工具_git&svn