feat(solutions): add is-palindrome/c/function

challenges/is-palindrome/solutions/c/function/string.h

@@ -0,0 +1,43 @@
+#ifndef STRING_H
+#define STRING_H
+
+#include <stdbool.h>
+
+/**
+ * @brief Converts all the alphabetic characters in a string to uppercase.
+ *
+ * @param string
+ * @return char*
+ */
+char* string_to_upper(const char* string);
+
+/**
+ * @brief Reverse the characters in an array.
+ *
+ * @param string
+ * @return char*
+ */
+char* string_reverse(const char* string);
+
+/**
+ * @brief Returns true if the string is a palindrome (a palindrome is a word,
+ * number, phrase, or other sequence of characters which reads the same backward
+ * as forward).
+ *
+ * @param string The string to check.
+ * @return true if the string is a palindrome, false otherwise.
+ */
+bool string_is_palindrome(const char* string);
+
+/**
+ * @brief Replace all the occurrences of search_value into replace_value in
+ * the string.
+ *
+ * @param string
+ * @param search_value A character search value.
+ * @param replace_value A character containing the text to replace for match.
+ * @return char*
+ */
+char* string_replace(const char* string, char search_value, char replace_value);
+
+#endif