adding atoi_superscript and isdigit_superscript

srcs/ft_isdigit_superscript.c

@@ -0,0 +1,55 @@
+#include "libft.h"
+
+/**
+ * Checks if the UTF-8 character at `input` is a superscript digit (², ³, ⁰-⁹).
+ * If it is, sets `*size` to the number of bytes in the character (2 or 3).
+ * Returns 1 if true, 0 otherwise.
+ */
+int ft_isdigit_superscript(const char *input, int *size)
+{
+    if (size != NULL)
+    {
+        *size = 0; // Default to 0 if not a superscript digit
+    }
+
+    // 2-byte UTF-8 superscript digits: ² (U+00B2) and ³ (U+00B3) ---
+    // In UTF-8, 2-byte characters start with a byte in the range 0xC0-0xDF.
+    // For superscript ² and ³:
+    //   - First byte: 0xC2 (binary: 11000010)
+    //   - Second byte: 0xB2 (²) or 0xB3 (³) (binary: 10110010 or 10110011)
+    if ((uint8_t)*input == 0xC2) // Check if first byte is 0xC2 (start of 2-byte UTF-8)
+    {
+        // Check if the second byte matches ² (0xB2) or ³ (0xB3)
+        if ((uint8_t)*(input + 1) == 0xB2 || (uint8_t)*(input + 1) == 0xB3)
+        {
+            if (size != NULL)
+            {
+                *size = 2; // 2-byte character
+            }
+            return 1; // Valid superscript digit (² or ³)
+        }
+    }
+    // 3-byte UTF-8 superscript digits: ⁰ (U+2070) to ⁹ (U+2079) ---
+    // In UTF-8, 3-byte characters start with a byte in the range 0xE0-0xEF.
+    // For superscript ⁰-⁹:
+    //   - First byte: 0xE2 (binary: 11100010)
+    //   - Second byte: 0x81 (binary: 10000001)
+    //   - Third byte: 0xB0 (⁰) to 0xB9 (⁹) (binary: 10110000 to 10111001)
+    else if ((uint8_t)*input == 0xE2) // Check if first byte is 0xE2 (start of 3-byte UTF-8)
+    {
+        // Check if the second byte is 0x81 (part of the 3-byte sequence for ⁰-⁹)
+        if ((uint8_t)*(input + 1) == 0x81)
+        {
+            // Check if the third byte is in the range 0xB0-0xB9 (⁰ to ⁹)
+            if ((uint8_t)*(input + 2) >= 0xB0 && (uint8_t)*(input + 2) <= 0xB9)
+            {
+                if (size != NULL)
+                {
+                    *size = 3; // 3-byte character
+                }
+                return 1; // Valid superscript digit (⁰-⁹)
+            }
+        }
+    }
+    return 0;
+}