I feel like this is a really silly question, but I can't seem to find an answer anywhere!
Is it possible to get a group of chars from a char array? to throw down some pseudo-code:
char arry[20] = "hello world!";
char part[10] = arry[0-4];
printf(part);
output:
hello
So, can I get a segment of chars from an array like this without looping and getting them char-by-char or converting to strings so I can use substr()?
You could use memcpy (or strncpy) to get a substring:
memcpy(part, arry + 5 /* Offset */, 3 /* Length */);
part[3] = 0; /* Add terminator */
On another aspect of your code, note that doing printf(str) can lead to format string vulnerabilities if str contains untrusted input.
In short, no. C-style "strings" simply don't work that way. You will either have to use a manual loop, or strncpy(), or do it via C++ std::string functionality. Given that you're in C++, you may as well do everything with C++ strings!
Side-note
As it happens, for your particular example application, you can achieve this simply via the functionality offered by printf():
printf("%.5s\n", arry);
As Oli said, you'd need to use C++ std::string functionality. In your example:
std::string hello("Hello World!");
std::string part(hello.substr(0, 5)); // note it's <start>, <length>, so not '0-4'
std::cout << part;
Well, you do mention the two obvious approaches. The only thing I can think of would be to define your own substring type to work off character arrays:
struct SubArray
{
SubArray(const char* a, unsigned s, unsigned e)
:arrayOwnedElseWhere_(a),
start_(s),
end_(e)
{}
const char* arrayOwnedElseWhere_;
unsigned start_;
unsigned end_;
void print()
{
printf_s("%.*s\n", end_ - start_ + 1, arrayOwnedElseWhere_ + start_);
}
};
Since C++17, you can use std::string_view to accomplish this:
char arry[20] = "hello world!";
auto part = std::string_view{arry, 5};
std::cout << part;
See it here: https://coliru.stacked-crooked.com/a/7ca65f2c8e8e46b4
C++20 also includes std::span, which is an option if you want to deal with ranges that are not just characters.
