How to convert a string such as "12|34|56|78" to and output of 12, 34, 56, 78 in c++

Question

i have to make a Convert constructor that takes a string. This string will hold the integers as a string of characters, numbers are separated by the character |. For example, if the parameter is the following string “12|34|56|78”, the resulting object will have the following values: 12, 34, 56, and 78.

for(int i=0; i<8; i++)
{
    if(s[i]!='|')
        cout<<s[i]<<s[i+1]<<", ";

}

this is what ive done so far but the output i get is "12, |2, 34, |3.." how do i make it "12, 34, 56, 78" ?

Answer 1

As-is you are printing out the | character even when the if condition is true. Using your approach modify the code to:

std::string s = "12|34|56|78";
for (std::size_t i = 0; i < s.size(); i++)  {
    if (s[i] == '|') {
        std::cout << ", ";
    }
    else {
        std::cout << s[i];
    }
}

If you want to modify the string itself then combine the std::string::find and std::string::replace functions as shown in Shreevardhan's answer.

Answer 2

Simply do a find and replace all

std::string s("12|34|56|78");
for (auto f = s.find('|'); f != string::npos; f = s.find('|')) {
    s.replace(f, 1, ", ");
}
std::cout << s << std::endl;

or, if you have a C-style string and just want the required output

char s[] = "12|34|56|78";

for (int i = 0; s[i]; i++) {
    if (s[i] == '|') {
        cout << ", ";
    }
    else {
        cout << s[i];
    }
}

Answer 3

If you want to change the string with the '|'s to a string with ','s, you can try to use the function replace from std.

std::replace( s.begin(), s.end(), '|', ',');

Answer 4

What you need to create is a string split method:

//Split string -- reusable
vector<string> splitString(string str, string delimiter)
{
  vector<string>v;
  string token;
  size_t pos = 0;

  while((pos = str.find(delimiter)) != string::npos)
    {
      token = str.substr(0, pos);
      v.push_back(token);
      str.erase(0, str.find(delimiter) + delimiter.length());
    }
  v.push_back(str);
  return v;
}

So use the '|' as a delimiter and you'll get the following result :) !

Answer 5

If you just use the STL you don't have use a loop.

#include <iostream>
#include <string>
#include <algorithm>
int main() {
    std::string s = “12|34|56|78”;
    std::replace(s.begin(),s.end(),'|',',');
    std::cout << s << '\n';
    return 0;
}

Listen to Stephan T. Lavavej's STL lectures, if you have time. They are fun! Link

Answer 6

Well if you just want a new string with the output you specified, you can do as simple as replacing the delimiter.(you can also copy new string and modify)

#include<bits/stdc++.h>
using namespace std;

int main()
{
string str="12|34|5|100";

 for(int i=0;i<str.length();i++)
 {
  if(str[i]=='|')
    str[i]=',';
 }

    cout<<str<<endl;
    return 0;
}

Answer 7

Have a look at strtok. It's a standard library function.

Citing the source:

char * strtok ( char * str, const char * delimiters );A sequence of calls to this function split str into tokens, which are sequences of contiguous characters separated by any of the characters that are part of delimiters.

/* strtok example */
#include <stdio.h>
#include <string.h>

int main ()
{
  char str[] ="- This, a sample string.";
  char * pch;
  printf ("Splitting string \"%s\" into tokens:\n",str);
  pch = strtok (str," ,.-");
  while (pch != NULL)
  {
    printf ("%s\n",pch);
    pch = strtok (NULL, " ,.-");
  }
  return 0;
}