Add Binary to Hexadecimal Converter (#589)

Author: cyrixninja

src/conversions/binary_to_hexadecimal.rs

@@ -0,0 +1,102 @@
+// Author : cyrixninja
+// Binary to Hex Converter : Converts Binary to Hexadecimal
+// Wikipedia References  : 1. https://en.wikipedia.org/wiki/Hexadecimal
+//                         2. https://en.wikipedia.org/wiki/Binary_number
+
+static BITS_TO_HEX: &[(u8, &str)] = &[
+    (0b0000, "0"),
+    (0b0001, "1"),
+    (0b0010, "2"),
+    (0b0011, "3"),
+    (0b0100, "4"),
+    (0b0101, "5"),
+    (0b0110, "6"),
+    (0b0111, "7"),
+    (0b1000, "8"),
+    (0b1001, "9"),
+    (0b1010, "a"),
+    (0b1011, "b"),
+    (0b1100, "c"),
+    (0b1101, "d"),
+    (0b1110, "e"),
+    (0b1111, "f"),
+];
+
+fn bin_to_hexadecimal(binary_str: &str) -> String {
+    let binary_str = binary_str.trim();
+
+    if binary_str.is_empty() {
+        return String::from("Invalid Input");
+    }
+
+    let is_negative = binary_str.starts_with('-');
+    let binary_str = if is_negative {
+        &binary_str[1..]
+    } else {
+        binary_str
+    };
+
+    if !binary_str.chars().all(|c| c == '0' || c == '1') {
+        return String::from("Invalid Input");
+    }
+
+    let padded_len = (4 - (binary_str.len() % 4)) % 4;
+    let binary_str = format!("{:0width$}", binary_str, width = binary_str.len() + padded_len);
+
+    // Convert binary to hexadecimal
+    let mut hexadecimal = String::with_capacity(binary_str.len() / 4 + 2);
+    hexadecimal.push_str("0x");
+
+    for chunk in binary_str.as_bytes().chunks(4) {
+        let mut nibble = 0;
+        for (i, &byte) in chunk.iter().enumerate() {
+            nibble |= ((byte - b'0') as u8) << (3 - i);
+        }
+
+        let hex_char = BITS_TO_HEX
+            .iter()
+            .find(|&&(bits, _)| bits == nibble)
+            .map(|&(_, hex)| hex)
+            .unwrap();
+        hexadecimal.push_str(hex_char);
+    }
+
+    if is_negative {
+        format!("-{}", hexadecimal)
+    } else {
+        hexadecimal
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_empty_string() {
+        let input = "";
+        let expected = "Invalid Input";
+        assert_eq!(bin_to_hexadecimal(input), expected);
+    }
+
+    #[test]
+    fn test_invalid_binary() {
+        let input = "a";
+        let expected = "Invalid Input";
+        assert_eq!(bin_to_hexadecimal(input), expected);
+    }
+
+    #[test]
+    fn test_binary() {
+        let input = "00110110";
+        let expected = "0x36";
+        assert_eq!(bin_to_hexadecimal(input), expected);
+    }
+
+    #[test]
+    fn test_padded_binary() {
+        let input = " 1010   ";
+        let expected = "0xa";
+        assert_eq!(bin_to_hexadecimal(input), expected);
+    }
+}