使用C ++中的istringstream将字符串拆分为整数 [英] Splitting a string into integers using istringstream in C++

问题描述

我试图使用 istringstream 将一个简单的字符串拆分为一系列整数：

  #include< string> 
 #include< iostream> 
 #include< sstream> 
 #include< vector> 
 
 using namespace std; 
 
 int main（）{
 
 string s =1 2 3; 
 istringstream iss（s）; 
 
 while（iss）
 {
 int n; 
 iss>> n; 
 cout<< *<< n<< endl; 
} 
} 
  

我得到：

  * 1 
 * 2 
 * 3 
 * 3 
  pre> 
 
 
为什么最后一个元素总是出现两次？如何解决？
解决方案
这是出来两次，因为你的循环是错误的， http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.5\">http://www.parashift.com/c++-faq-lite/input-output.html# while（iss.eof（））与没有区别。 
 
 
 
具体来说，在第三次循环迭代中， iss> n 成功并获得您的 3 ，并保持流处于良好状态。由于这个好的状态，循环然后运行第四次，并且直到下一个（第四个） iss>> n 后续失败，循环条件被破坏。但在第四次迭代结束之前，您仍然输出 n  ...第四次。
 
 
 
 p> 
 
 
  #include< string> 
 #include< iostream> 
 #include< sstream> 
 #include< vector> 
 
 using namespace std; 
 
 int main（）
 {
 string s =1 2 3; 
 istringstream iss（s）; 
 int n; 
 
 while（iss>> n）{
 cout< *<< n<< endl; 
} 
} 
  
 
I'm trying to use istringstream to split a simple string into a series of integers:
#include <string>
#include <iostream>
#include <sstream>
#include <vector>

using namespace std;

int main(){

    string s = "1 2 3"; 
    istringstream iss(s);   

    while (iss)
    {
        int n;
        iss >> n;
        cout << "* " << n << endl;
    } 
}
And i get:
* 1
* 2
* 3
* 3
Why is the last element always coming out twice? How to fix it?
解决方案
It's coming out twice because your looping is wrong, as explained (indirectly) at http://www.parashift.com/c++-faq-lite/input-output.html#faq-15.5 (while (iss) is not dissimilar from while (iss.eof()) in this scenario).

Specifically, on the third loop iteration, iss >> n succeeds and gets your 3, and leaves the stream in a good state. The loop then runs a fourth time due to this good state, and it's not until the next (fourth) iss >> n subsequently fails that the loop condition is broken. But before that fourth iteration ends, you still output n... a fourth time.

Try:
#include <string>
#include <iostream>
#include <sstream>
#include <vector>

using namespace std;

int main()
{
    string s = "1 2 3"; 
    istringstream iss(s);   
    int n;

    while (iss >> n) {
        cout << "* " << n << endl;
    } 
}


                        
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