std::string::data() in C++
The data() function writes the characters of the string into an array. It returns a pointer to the array, obtained from conversion of string to the array. Its Return type is not a valid C-string as no ‘\0’ character gets appended at the end of array.
const char* data() const; char* is the pointer to the obtained array. Parameters : None
- std::string::data() returns an array that is owned by the string. Thus, the caller must not modify or free the memory.
Let’s take same example where ptr points to final array.
ptr = 'a'; this will raise an error as ptr points to an array that is owned by the string, in other words ptr is now pointing to constant array and assigning it a new value is now not allowed.
- Return value of data() is valid only until the next call of a non-constant member function for the same string.
Suppose, str be the original string which is required to be converted in an array
// converts str in an array pointed by pointer ptr. const char* ptr = str.data(); // Bad access of str after modification // of original string to an array str += "hello"; // invalidates ptr // Now displaying str with reference of ptr // will give garbage value cout << ptr; // Will give garbage value
Content of Original String : GeeksforGeeks Length of original String : 13 Content of transformed string : GeeksforGeeks After data(), length: 13
Here, we can easily notice, both contents and length of original string and transformed array are same.
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