tell cin to stop reading at newline

Question

Suppose I want to read line a of integers from input like this:

1 2 3 4 5\\n

I want cin to stop at \'\\n\' character but cin doesn\'t seem

Answer 1

Use std::getline, this will do the trick

Answer 2

You can use the getline method to first get the line, then use istringstream to get formatted input from the line.

Answer 3

From this link, it is quite simple to achieve this.

#include <stdio.h>
int main(void) {
    int i=0,size,arr[10000];
    char temp; 
    do{
        scanf("%d%c", &arr[i], &temp); 
        i++; 
        } while(temp!= '\n');

    size=i; 
    for(i=0;i<size;i++){ 
        printf("%d ",arr[i]); 
    } 
    return 0;
}

Answer 4

You can read all whitespace by setting noskipws on the istream:

#include <ios>
#include <iostream>
#include <vector>

using std::vector;

vector<int> getc() {
    char c;
    vector<int> cl;
    std::cin >> std::noskipws;
    while (std::cin >> c && c != '\n') {
        cl.push_back(c);
        std::cin >> c;
    }
    return cl;
}

If the standard input contains only a single line, you might as well construct the vector with the istream_iterator:

#include <iostream>
#include <iterator>
#include <vector>

using std::vector;

vector<int> getc() {
    // Replace char with int if you want to parse numbers instead of character codes
    vector<int> cl{
        std::istream_iterator<char>(std::cin),
        std::istream_iterator<char>()
    };
    return cl;
}

Answer 5

getchar() is more efficient than cin when working with characters at this situation

I tried to do the same with a line of characters with unknown length and want it to stop at a newline but it has an infinite loop and haven't detect the newline, so I just used getchar() instead of cin and it works

Answer 6

Use getline and istringstream:

#include <sstream>
/*....*/
vector<int> getclause() {
  char c;
  vector<int> cl;
  std::string line;
  std::getline(cin, line);
  std::istringstream iss(line);
  while ( iss >> c) {    
    cl.push_back(c);
  }
  return cl;
}