PAT(Advanced Level)1001 A+B Format

分手后的思念是犯贱 2022-05-11 11:12 126阅读 0赞

1001 A+B Format （20 分）

Calculate a+b and output the sum in standard format -- that is, the digits must be separated into groups of three by commas (unless there are less than four digits).

### Input Specification: ###

Each input file contains one test case. Each case contains a pair of integers a and b where −106≤a,b≤106. The numbers are separated by a space.

### Output Specification: ###

For each test case, you should output the sum of a and b in one line. The sum must be written in the standard format.

### Sample Input: ###

-1000000 9

### Sample Output: ###

-999,991

/*	Sample Input:-1000000 9
    	Sample Output:-999,991
    */
    #include <iostream>
    #include <algorithm> 
    #include <string>
    using namespace std;
    int main(){
    	int a, b, sum;
    	cin >> a >> b;
    	sum = a + b;
    	string s = to_string(sum);//转化为字符型数组
    	if(s[0] == '-') {
    		cout << "-";
    		s.erase(0, 1); //删除从下标从0开始的一个字符 
    	}
    	reverse(s.begin(), s.end());//由于添加","从后往前加的，所以需要先转置一下
    	int len = (int)s.size();
    	for(int i = 3; i < len; i += 3) { //每隔3个数字插入一个"," 
    		s.insert(i, ",");
    		i++; //插完的","也算一个位置的,故要往后移一位的
    		len++; //插入","以后s的总长度要加1 
    	}	
    	reverse(s.begin(), s.end());
    	cout << s; 
    	return 0;
    }

## string字符串操作： ##

*  erase  
    原型：  
    （1）string& erase ( size\_t pos = 0, size\_t n = npos );  
    （2）iterator erase ( iterator position );  
    （3）iterator erase ( iterator first, iterator last );  
    用法：  
    （1）erase(pos,n); 删除从pos开始的n个字符，比如erase(0,1)就是删除第一个字符  
    （2）erase(position);删除position处的一个字符(position是个string类型的迭代器)  
    （3）erase(first,last);删除从first到last之间的字符（first和last都是迭代器）
 *  insert  
    原型：  
    string &insert(int p0, const char \*s);  
    string &insert(int p0, const char \*s, int n);  
    string &insert(int p0,const string &s);  
    string &insert(int p0,const string &s, int pos, int n);  
    //前4个函数在p0位置插入字符串s中pos开始的前n个字符  
    string &insert(int p0, int n, char c);//此函数在p0处插入n个字符c  
    iterator insert(iterator it, char c);//在it处插入字符c，返回插入后迭代器的位置  
    void insert(iterator it, const\_iterator first, const\_iterator last);//在it处插入\[first，last）之间的字符  
    void insert(iterator it, int n, char c);//在it处插入n个字符c
 *  to\_string函数 C++11 新增方法  
    string to\_string (int val);  
    string to\_string (long val);  
    string to\_string (long long val);  
    string to\_string (unsigned val);  
    string to\_string (unsigned long val);  
    string to\_string (unsigned long long val);  
    string to\_string (float val);  
    string to\_string (double val);  
    string to\_string (long double val)
 *  reverse函数  
    数组转置 reverse(v.begin(),v.end())