Find how many strings in istringstream

Question

I want to know how many strings there are in my variable when I use istringstream:

string cadena;
int num;

istringstream ss(cadena);
ss >> num;
int n = ss.size();  // This doesn't work

For example if cadena is: "1 2 3 4", when I use istringstream I want to know how many strings are in ss (in this case 4).

which characters do you consider as terminating a string, only spaces? — perreal, Mar 02 '12 at 18:39
I use istringstream because I don't want to count the spaces between the numbers. — EricJ, Mar 02 '12 at 18:39
Why do you want this information? If you need the numeric values, just using `std::istream_iterator( ss )` in the initializer for `std::vector< int >` should do the trick. — James Kanze, Mar 02 '12 at 19:38

score 2 · Answer 1 · answered Mar 02 '12 at 18:44

2

The only way of which I'm aware is to parse the strings out to see. std::distance with an istream_iterator can do that for you:

std::distance(std::istream_iterator<string>(ss), 
              std::istream_iterator<string>());

answered Mar 02 '12 at 18:44

Jerry Coffin

476,176
80
629
1,111

After which, of course, he's read the stream, and has to create it again to reread it. – James Kanze Mar 02 '12 at 19:34
@JamesKanze: Yup -- though of course that's pretty easy to do with a stringstream. The obvious alternative would be to read the data into a vector, then find the size of the vector. – Jerry Coffin Mar 02 '12 at 19:50

perreal · Answer 2 · 2012-03-02T20:10:53.807

1

#include <iostream>
#include <sstream>
#include <algorithm>
#include <ctype.h>

int  main()
{
  std::string str = ss.str();

  // int c = (int) std::count_if (str.begin(), str.end(), isspace) + 1;
  int c = 1;  // 0
  for (unsigned int i = 0; i <str.size(); i++ ) 
    if (isspace(str[i])) 
      c++;
  std::cout << c;
  return 1;
}

edited Mar 02 '12 at 20:10

answered Mar 02 '12 at 18:46

perreal

94,503
21
155
181

That's because it's name is `std::count_if`. – James Kanze Mar 02 '12 at 19:32
But of course, that doesn't tell you anything about how many fields there might be. – James Kanze Mar 02 '12 at 19:32
Still doesn't recognise this fuction. – EricJ Mar 02 '12 at 19:58
The idea was to do it without loops,but i guees it's impossible,thx anyway :) – EricJ Mar 02 '12 at 20:12

score 0 · Answer 3 · edited Jul 19 '13 at 04:02

0

You can do something like, add while loop

while(ss>>cadena) {

edited Jul 19 '13 at 04:02

Rajat Modi

1,343
14
38

answered Jul 19 '13 at 03:31

James

1

Find how many strings in istringstream

3 Answers3