Question

I want to initialize a char array using pointers, on the fly.That is user giving input do not know the size of array.User keeps on giving input until return is pressed.Condition here is to:

• Use pointers to initialize
• Not to pass size of array in advance.

Answer 1

Assuming a C question, how about (untested):

char *arr = malloc(10);
size_t size = 10, index = 0;
int ch;
while ((ch = getc(stdin)) != EOF && ch != '\n' && ch != '\r') {
    if (index >= size) {
        size *= 2;
        arr = realloc(arr, size); /* XXX check it first. */
    }
    arr[index++] = ch;
}
arr[index] = 0;

If it’s really a C++ question you want std::getline with a std::string.