A collection of common “tricks” in Java involving characters, ASCII/Unicode values, and simple conversions.
These are handy for DSA problems, competitive programming, or just quick conversions without heavy libraries.
| Trick | Description | Example |
|---|---|---|
ch - '0' |
Convert digit char → int | '7' - '0' = 7 |
num + '0' |
Convert digit int → char | 7 + '0' = '7' |
ch - 'A' + 1 |
Alphabet position (uppercase) | 'C' - 'A' + 1 = 3 |
ch - 'a' + 1 |
Alphabet position (lowercase) | 'd' - 'a' + 1 = 4 |
ch + 32 |
Uppercase → Lowercase (ASCII diff 32) | 'A' + 32 = 'a' |
ch - 32 |
Lowercase → Uppercase | 'z' - 32 = 'Z' |
(int)ch |
ASCII / Unicode value of a character | (int)'!' = 33 |
char c = 65; |
Directly assign ASCII value → char | c = 'A' |
| Check digit | c >= '0' && c <= '9' |
'5' → digit |
| Check uppercase | c >= 'A' && c <= 'Z' |
'K' → uppercase |
| Check lowercase | c >= 'a' && c <= 'z' |
'm' → lowercase |
| Hexadecimal conversion | (c >= '0' && c <= '9') ? (c - '0') : (c - 'A' + 10) |
'B' → 11 |