How to split a string into an array of strings in C?-CodePudding

I've been having this issue for quite a long time so I wanted to ask how to split a string into an array of "Words"?

I've tried strtok and strtok_r but it doesn't seem to work the way I intend it to:

    char str[] = "This is a sentence.";

    // Returns first token
    char* token = strtok(str, " ");
    char *tokens[500];
  
    // Keep printing tokens while one of the
    // delimiters present in str[].
    
    
    for (int i = 0; i < 3; i  ) {
        while (token != NULL) {
            token = strtok(NULL, " ");
            strcpy(tokens[i], token);
        }
        printf("%s\n", tokens[i]);
    }
    
    return 0;

This doesn't print out anything, can anyone help?

CodePudding user response：

If you want to split str in tokens and store the tokens in buffer tokens, here's how you can do it (please have a look at the comments I added):

char str[] = "This is a sentence.";

// Initialize tokens to NULL
char* tokens[500] = {0};

// Split the string in tokens and count the tokens:
size_t tokenCount = 0;
static size_t const max_token_count = sizeof(tokens) / sizeof(tokens[0]);
for (char* token = strtok(str, " ");
     token != NULL                  &&   tokenCount != max_token_count;
//   ^ Loop until there are tokens  and  ^ buffer not overflown
     token = strtok(NULL, " ")) {

    tokens[tokenCount  ] = token;
    //                   ^ No need to allocate memory here, if you
    //                     are going to use tokens before str goes
    //                     out of scope.

}

// You may handle the case when there are more tokens in str that
// couldn't fit into buffer tokens here

for (size_t i = 0; i != tokenCount;   i)
    puts(tokens[i]);

Output

This
is
a
sentence.

Please note that, at the end of the snippet above, str will be modified: the spaces will be replaced by character '\0':

char str[] = "This is a sentence.";
//                ^  ^ ^

So, if you

puts(str);

you'll only get

This

CodePudding user response：

here is a possible help if I understand correctly what your needs are. I use tabs and remove all the calls for strtok.

From this code you will print only the first word, I let you find the way to print all of them :)

int main(){
    char str[] = "This is a sentence.";

    // Returns first token
    char tokens[500];
  
    // Keep printing tokens while one of the
    // delimiters present in str[].
    
    
    for (int i = 0; i < sizeof(tokens); i  ) {
        if (str[i] == ' '){
            break;
        }
        tokens[i] = str[i];
    }
    printf("%s\n", tokens);

    
    return 0;
}

EDIT

full solution:

int main(){
    char str[] = "This is a sentence.";
    char tokens[500];
    memset(tokens,'\0', sizeof(tokens));

        for(int i=0, j=0; i< sizeof(tokens); i  )
        {

            if (str[i] == ' ' || str[i] == '\n' || str[i] == 0) {
                printf("%s\n", tokens);
                //reinit buffer token
                memset(tokens,'\0', sizeof(tokens));
                j=0;            
            }else{
                tokens[j] = str[i];
                j  ;
            }
            if (str[i] == 0) {
                break;              //end of string found, exit the loop
            }

        }
    return 0;
}

Output

This  
is  
a  
sentence.