(c++) Elements of Array into String?

Question

Can somebody help me in converting some elements of char array[] into String. I'm still learning strings.

char input[40] = "save filename.txt";
int j;
string check;
for (int i = 0; input[i] != '\0'; i++)
{
   if (input[i] == ' ')
   {
      j = i+1;
      break;
   }
}
int index;
for (int m = 0; arr[j] != '\0'; m++)
{
    check[m] = arr[j];
    j++;
    index = m; //to store '\0' in string ??
}
check[index] = '\0';
cout << check; //now, String should output 'filename.txt" only

Not a very well-formed question -- what have you tried? And what didn't work about it? — RobP
– RobP, Commented Dec 8, 2014 at 19:11
I don't think that edit by Houssem should have been approved. Changed string to String and removed a potential example. — crashmstr
– crashmstr, Commented Dec 8, 2014 at 19:35
@crashmstr he is newbye and should learn write correctly and not to put non-informative lines — Houssam Badri
– Houssam Badri, Commented Dec 9, 2014 at 13:23
@HoussemBdr and when is a string String? Your changes were not significantly better in my opinion, and I would not have approved them had I seen them before they took place. — crashmstr
– crashmstr, Commented Dec 9, 2014 at 13:37

Houssam Badri · Accepted Answer · 2014-12-08 19:17:20Z

3

The string class has a constructor that takes a NULL-terminated C-string:

char arr[ ] = "filename.txt";

string str(arr);


//  You can also assign directly to a string.

str = "filename.txt";

answered Dec 8, 2014 at 19:17

Houssam Badri

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Comments

Felix Glas · Accepted Answer · 2014-12-08 20:01:53Z

The ctor of std::string has some useful overloads for constructing a string from a char array. The overloads are about equivalent to the following when used in practice:

Taking a pointer to constant char, i.e. a null-terminated C-string.
```
string(const char* s);
```
The char array must be terminated with the null character, e.g. {'t', 'e', 's', 't', '\0'}. String literals in C++ is always automatically null-terminated, e.g. "abc" returns a const char[4] with elements {'a', 'b', 'c', '\0'}.
Taking a pointer to constant char and specified number of characters to copy.
```
string(const char* s, size_type count);
```
Same as above but only count number of characters will be copied from the char array argument. The passed char array does not necessarily have to be null-terminated.

Taking 2 iterators.

string(InputIt first, InputIt last);

Can be used to construct a string from a range of characters, e.g.

const char[] c = "character array";
std::string s{std::next(std::begin(c), 10), std::end(c)}; // s == "array".

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