Tokenizing a string in C++

Question

Description: Building basic code in C++ for tokenizing string(whitespaces included).

The main idea: To call a local function that counts all the whitespaces in a string using their null value for the beginning.

The problem: Early termination before reaching the second token.

#include "stdafx.h"
#include <iostream>
#include <cstring>

using namespace std;

char *next_token = NULL;

int count_spaces(const char *p);

char *p;

int main() {
    char s[81];

    cout << "Input a string : ";
    cin.getline(s, 81);

    p = strtok_s(s, ", ", &next_token);

    while (p != nullptr) {
        cout << p << endl;
        p = strtok_s(nullptr, ", ", &next_token);
    }

    count_spaces(p);

    cout << count_spaces(p);

    return 0;
}

int count_spaces(const char *p) {
    int number = 0, len;
    if (p == NULL) {
        return 0;
    }

    while (*p) {
        if (*p == '1')
            len = 0;
        else if (++len == 1)
            number++;
        p++;
    }
}

Any assistance would be appreciated.

Answer 1

The tokenizing part of your program works. But when you call count_spaces(p), p is always NULL (or nullptr which is pretty much the same).

Maybe you want this (I left out the tokenizing part):

#include <iostream>
#include <cstring>

using namespace std;

int count_spaces(const char *p);

int main() {
  char s[81];
  cout << "Input a string : ";
  cin.getline(s, sizeof s);      // using sizeof s is better than repeating "81"

  cout << "Number of spaces in string: " << count_spaces(s) << endl;
  return 0;
}

int count_spaces(const char *p) {
  if (p == NULL) {
    return 0;
  }

  int nbofspaces = 0;

  while (*p) {
    if (*p == ' ') { 
      nbofspaces++;
    }
    p++;
  }

  return nbofspaces;
}

Disclaimer: this is poor C++ code. It is rather what you would do in C, but this code sticks as closely as possible to the OP's original code.