java 读取未知数量的输入
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Reading an unknown number of inputs
提问by tianz
I need to read an unknown number of inputs using either C++ or Java. Inputs have exactly two numbers per line. I'd need to use cinor a System.inScannerbecause input comes from the console, not from a file.
我需要使用 C++ 或 Java 读取未知数量的输入。输入每行正好有两个数字。我需要使用cinor aSystem.inScanner因为输入来自控制台，而不是来自文件。
Example input:
示例输入：
1 2
3 4
7 8
100 200
121 10
I want to store the values in a vector. I have no idea how many pairs of numbers I have. How do I design a whileloop to read the numbers so I can put them into a vector?
我想将值存储在向量中。我不知道我有多少对数字。如何设计一个while循环来读取数字，以便将它们放入向量中？
回答by chris
You can use an idiomatic std::copyin C++: (see it work here with virtualized input strings)
您可以std::copy在 C++ 中使用惯用语：（请参阅此处使用虚拟化输入字符串工作）
std::vector<int> vec;
std::copy (
std::istream_iterator<int>(std::cin),
std::istream_iterator<int>(),
std::back_inserter(vec)
);
That way, it will append onto the vector each time an integer is read from the input stream until it fails reading, whether from bad input or EOF.
这样，每次从输入流中读取整数时，它都会附加到向量上，直到读取失败，无论是从错误输入还是 EOF。
回答by Osiris
Java:
爪哇：
Scanner sc = new Scanner(System.in);
String inputLine;
while(sc.hasNextLine()) {
inputLine = sc.nextLine();
//parse inputLine however you want, and add to your vector
}
回答by Rao Virinchi
Instead of using a buffered reader, one can use Scanner as follows to accomplish the same
除了使用缓冲读取器之外，您还可以使用 Scanner 来完成相同的操作
import java.util.*;
public class Solution {
公共课解决方案{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
while(true)
{
String Line = new String(scan.nextLine());
if(Line.length()==0)
{
break;
}
}
}
}
}
回答by Hrithik Raj
For someone looking for less fancier C++ code:
对于寻找不那么花哨的 C++ 代码的人：
#include<iostream>
#include<vector>
int main(){
std::vector<int>inputs; //any container
for(int i;std::cin>>i;) //here the magic happens
inputs.push_back(i); //press Ctrl+D to break the loop
for(int num:inputs) //optional
std::cout<<num<<endl;
}
回答by vaibhav taneja
Only workaround I found :
我发现的唯一解决方法：
import java.io.*;
class Solution {
public static void main(String args[] ) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int i=1 ;
String line =br.readLine();
while(line.length()>0){
System.out.println(line);
line = br.readLine();
}
}
}
