Problem

Given a single character c, return its ASCII (Unicode code point) value. As follow-ups: convert an integer back to its character, and explain how character arithmetic ('a' + 1, c - '0') works.

Input / Output

• Input: character c.
• Output: integer.

Examples

Input	Output
'A'	65
'a'	97
'0'	48
' '	32
'~'	126

Constraints

• c is a printable ASCII character (32–126).

Approach

Every language exposes the code point directly: ord(c) in Python, (int) c in C/C++/Java, c.charCodeAt(0) in JavaScript. The reverse is chr(n) / (char) n / String.fromCharCode(n).

What interviewers actually probe with this warm-up:

• Digits '0'..'9' are contiguous (48–57), so c - '0' converts a digit character to its numeric value.
• Uppercase 'A'..'Z' are 65–90 and lowercase 'a'..'z' are 97–122; they differ by 32, which is why c ^ 32 toggles case and c | 32 lowercases.
• Building a frequency array indexed by ord(c) - ord('a') is O(1) per character and is the basis of many string problems.
• Beyond ASCII, ord returns the Unicode code point; UTF-8 byte length is a separate concept.

Complexity

• Time: O(1)
• Space: O(1)

Reference solution (Python)

def ascii_value(c: str) -> int:
    return ord(c)

def char_from(n: int) -> str:
    return chr(n)

Test cases

Input	Expected
'A'	65
'a'	97
'0'	48
char_from(126)	'~'