How to fix 'No matching function for call to 'strtok''

Question

I'm trying to use the function strtok to tokenize an input from the user and then print out the result with new lines between each word. However, this error pops up.

#include <iostream>
#include <stdio.h>
#include <string.h>

using namespace std;

int main()
{
    string str;
    char *tokenPtr;

    cout << "Enter a sentence : " << endl;
    getline(cin, str);

    tokenPtr = strtok( str, " " ); // ERROR: No matching function for call to 'strtok'
    while( tokenPtr != NULL ) {
        cout << tokenPtr << endl;
        tokenPtr = strtok( NULL, " " );
    }

    return 0;
}

@Naoki Atkins strtok is used with character arrays while you are trying to use it with an object of the type std::string. — Vlad from Moscow, Aug 08 '19 at 09:23
You can always do str.c_str() to convert it to const char *. — The Marlboro Man, Aug 08 '19 at 09:30
@TheMarlboroMan `strtok` takes a pointer to `char` because it modifies the array — user7860670, Aug 08 '19 at 09:31
@VTT, sorry, I meant some hack like creating the char * by copying from c_str()... Still terrible considering the stream solution :). — The Marlboro Man, Aug 08 '19 at 09:33
@Vlad from Moscow, sorry, I meant that hacking a const char * in C++ is a terrible solution, specially when you can use streams :). If anything I meant that streams are the idiomatic way to do it!. — The Marlboro Man, Aug 08 '19 at 10:23

score 1 · Answer 1 · answered Aug 08 '19 at 09:30

The standard C function strtok is used with character arrays that contain strings.

So its first parameter has the type char * while you are supplying an argument of the type std::string.

You can use instead a standard string stream std::istringstream, For example

#include <iostream>
#include <string>
#include <sstream>

int main() 
{
    std::string s;

    std::cout << "Enter a sentence : ";

    std::getline( std::cin, s, '\n' );

    std::string word;

    for ( std::istringstream is( s ); is >> word; )
    {
        std::cout << word << '\n';
    }

    return 0;
}

The program output might look like

Enter a sentence : Hello Naoki Atkins
Hello
Naoki
Atkins

How to fix 'No matching function for call to 'strtok''

1 Answers1