Trying to use strtok() to seperate words in input

Question

Hi there, I'm trying to get strtok() to take a 50 character input and then display the words seperated by a space. For example if I input hello1 hello2 hello3. Can someone please advise where I'm wrong and why from a learning perspective.

https://code.sololearn.com/cUyC49BF0mRg/?ref=app
https://code.sololearn.com/cUyC49BF0mRg/?ref=app

Answer 1

Hi. Read this for better scanf understanding https://www.tutorialspoint.com/c_standard_library/c_function_scanf.htm
You should provide another format, not "%s". Also you don't use strtok properly. Example of strtok usage https://www.geeksforgeeks.org/strtok-strtok_r-functions-c-examples/

Answer 2

Try to correct solution for yourself. If you are completely stuck here is my solution.
https://code.sololearn.com/cJ9nPA27PzuZ/?ref=app

Answer 3

Thanks it seems I'm missing

// Keep printing tokens while one of the
// delimiters present in str[].
while (token != NULL) {
printf("%s\n", token);
token = strtok(NULL, "-");
}

Answer 4

You' re right. Also either use another delimeter instead of spaces or change scanf format

Answer 5

char array[50], input;
scanf("%s",&input);
char * token = strtok(input, " " );

while (token){
printf("%s\n", token);
token = strtok(NULL, " ");

return 0;
}

Hi Stephan, I know you suggested to remove %s, however I want to understand why I get error
"Makes pointer from interger without a cast"
What does this mean?

Answer 6

Do you know how C stores arrays in memory?

Answer 7

Not particularly, I've read the below to gain a better understanding. Makes pointer from interger without cast ? I understand a pointer is a variable with a memory address,
I'm assuming each element in array has got a memory address?

int* p;
// variable p is pointer to integer type

Im assuming in my program it's putting pointer addresses for each " " (space) in array."token" is the variable for these spaces ? was does this without cast referring to

int i;
// integer value
int i2 = *p;
// integer i2 is assigned

https://www.cs.bu.edu/teaching/cpp/string/array-vs-ptr/

Answer 8

Oh. I missed this comma in the first line of your code. Remove it.

Answer 9

But that doesn't make sense.
Both pointer and array variable store address in memory. Just one address of the first element. Try to run this code
https://code.sololearn.com/c7DmU3vQgFtH/?ref=app

Answer 10

Code has errors, so I changed it

Answer 11

So as you can see array and pointer variables actually are numbers that represent memory address.
After that you should understand & operator. This operator gives you address where variable is stored.
Suppose we declared char a;
&a gives you addres of value stored in variable.
So you can do something like this
char *p = &a;

Answer 12

Ran yours, it worked however it still warned "makes pointer from interger without a cast" I'm trying to understand this error.

Google says:
A char is a form of integer in C. You are assigning it into a char[] which is a pointer. Hence "converting integer to pointer".

Answer 13

I had different code in my mind.

Answer 14

At first you should add [50] in input declaration and add closing bracket

Answer 15

Code should run, but with some warnings

Answer 16

char input; - input is single character
char input[50]; - input is memory address

Answer 17

Ok thanks.
int main()

{

    char str[] = "Geeks-for-Geeks";

    // Returns first token

    char* token = strtok(str, "-");

    // Keep printing tokens while one of the

    // delimiters present in str[].

    while (token != NULL) {

        printf("%s\n", token);

        token = strtok(NULL, "-");

    }

    return 0;

I think I understand the above now basically a pointer variable is set for each "-" in array elements...which is marked NULL. And while token does not equal NULL print each element in array

Answer 18

Hi Stephan, back again. How do you compare a variable, which I'm assuming in "token" is a ptr address to a literal string. Should I be using a function such as strcmp?
https://code.sololearn.com/cy0vNDXAjjKD/?ref=app

Answer 19

Hi. You should. Pay attention at return value of strcmp, it becomes zero when strings are equal. Also you should remove ampersand symbols.

Answer 20

By the way. When you compare like this
token == "some text"
you actually compare adresses, not values ("some text" has type char[10]).