Convert Uppercase ASCII Letters
Company: Google
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
### Problem
Return a copy of s in which each uppercase English letter is replaced by its lowercase counterpart. Leave digits, punctuation, spaces and existing lowercase letters unchanged.
```cpp
class Solution {
public:
string toLowerCase(string s);
};
```
### Examples
**Example 1:**
```text
s = "Go-2!"
Output: "go-2!"
Explanation: Only G changes.
```
**Example 2:**
```text
s = "AZ az"
Output: "az az"
Explanation: The space and lowercase suffix stay unchanged.
```
### Constraints
- The string contains 1 through 100 characters.
- Every character is printable ASCII.
### Contract considerations
Use the printable ASCII contract, preserving all nonuppercase characters.
```hint Read the boundary condition
Which contiguous ASCII interval needs conversion?
```
### Boundary reminders
Use the printable ASCII contract, preserving all nonuppercase characters.
Overview: Convert Uppercase ASCII Letters. Return a copy of s in which each uppercase English letter is replaced by its lowercase counterpart.