string::copy
Copy a substring to another string.
Synopsis
std::size_t
copy(
    char* dest,
    std::size_t count,
    std::size_t pos = 0) const;
Description
Copies std::min(count, size() - pos) characters starting at index pos to the string pointed to by dest.
| 
 This function doesn’t put the null terminator after the copied characters.  | 
Return Value
The number of characters copied.
Parameters
| Name | Description | 
|---|---|
  | 
The number of characters to copy.  | 
  | 
The string to copy to.  | 
  | 
The index to begin copying from.  | 
Exceptions
| Type | Thrown On | 
|---|---|
  | 
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