23

I have a const char* variable which may have a value like "OpenStack:OpenStack1". I want to tokenize this const char* using strtok where the delimiter(which is of a const char* type) is ":" . But the problem is strtok is of following type: char * strtok ( char * str, const char * delimiters );

Which means I can't use const char* for the first input as it has to be char*. Could you say me how I can convert this const char* into char*?

Thank you.

the_naive
  • 2,936
  • 6
  • 39
  • 68

3 Answers3

24

Since strtok actually writes to your string, you need to make a writable copy of it to tokenize;

char* copy = strdup(myReadonlyString);
...tokenize copy...
free(copy);
Joachim Isaksson
  • 176,943
  • 25
  • 281
  • 294
  • 4
    A c++ way of making a copy would be `std::vector copy(myReadonlyString, myReadonlyString+strlen(myReadonlyString));`. You can then tokenize `copy->data()`. The compiler will de-allocate the copy automatically whenever it goes out of scope. – ManuelAtWork Feb 15 '16 at 12:55
  • 3
    @Manuel, the value you've stored in `copy` isn't null-terminated. Use `strlen(myReadonlyString) + 1` to ensure the input's terminator is included in the vector. – Rob Kennedy Apr 23 '18 at 18:33
2

Declare it as an array:

char tokenedStr[] = "OpenStack:OpenStack1";

if not possible, copy it to a char array.

MByD
  • 135,866
  • 28
  • 264
  • 277
0

You can make a copy of your non-modifiable string and then use strtok.

You can portably use malloc and strcpy to copy the string.

ouah
  • 142,963
  • 15
  • 272
  • 331