Merge pull request #586 from shellhub/feature

Convert integer to string

Author: realDuYuanChao

DIRECTORY.md

@@ -17,6 +17,7 @@
   * [Decimal To Octal](https://github.com/TheAlgorithms/C/blob/master/conversions/decimal_to_octal.c)
   * [Decimal To Octal Recursion](https://github.com/TheAlgorithms/C/blob/master/conversions/decimal_to_octal_recursion.c)
   * [Hexadecimal To Octal](https://github.com/TheAlgorithms/C/blob/master/conversions/hexadecimal_to_octal.c)
+  * [Int To String](https://github.com/TheAlgorithms/C/blob/master/conversions/int_to_string.c)
   * [Octal To Decimal](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_decimal.c)
   * [To Decimal](https://github.com/TheAlgorithms/C/blob/master/conversions/to_decimal.c)
 

conversions/int_to_string.c

@@ -0,0 +1,83 @@
+/**
+ * @file
+ * @brief Convert a positive integer to string (non-standard function)
+ * representation.
+ */
+#include <assert.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+/**
+ * Converts an integer value to a null-terminated string using the specified
+ * base and stores the result in the array given by str parameter.
+ * @param value Value to be converted to a string.
+ * @param dest pointer to array in memory to store the resulting null-terminated
+ * string.
+ * @param base Numerical base used to represent the value as a string, between 2
+ * and 16, where 10 means decimal base, 16 hexadecimal, 8 octal, and 2 binary.
+ * @returns A pointer to the resulting null-terminated string, same as parameter
+ * str.
+ * @note The destination array must be pre-allocated by the calling function.
+ */
+char *int_to_string(uint16_t value, char *dest, int base)
+{
+    const char hex_table[] = {'0', '1', '2', '3', '4', '5', '6', '7',
+                              '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
+
+    int len = 0;
+    do
+    {
+        dest[len++] = hex_table[value % base];
+        value /= base;
+    } while (value != 0);
+
+    /* reverse characters */
+    for (int i = 0, limit = len / 2; i < limit; ++i)
+    {
+        char t = dest[i];
+        dest[i] = dest[len - 1 - i];
+        dest[len - 1 - i] = t;
+    }
+    dest[len] = '\0';
+    return dest;
+}
+
+/** Test function
+ * @returns `void`
+ */
+static void test()
+{
+    const int MAX_SIZE = 100;
+    char *str1 = (char *)calloc(sizeof(char), MAX_SIZE);
+    char *str2 = (char *)calloc(sizeof(char), MAX_SIZE);
+
+    for (int i = 1; i <= 100; ++i) /* test 100 random numbers */
+    {
+        /* Generate value from 0 to 100 */
+        int value = rand() % 100;
+
+        // assert(strcmp(itoa(value, str1, 2), int_to_string(value, str2, 2)) ==
+        //        0);
+        snprintf(str1, MAX_SIZE, "%o", value);  //* standard C - to octal */
+        assert(strcmp(str1, int_to_string(value, str2, 8)) == 0);
+        snprintf(str1, MAX_SIZE, "%d", value); /* standard C - to decimal */
+        assert(strcmp(str1, int_to_string(value, str2, 10)) == 0);
+        snprintf(str1, MAX_SIZE, "%x", value); /* standard C - to hexadecimal */
+        assert(strcmp(str1, int_to_string(value, str2, 16)) == 0);
+    }
+
+    free(str1);
+    free(str2);
+}
+
+/** Driver Code */
+int main()
+{
+    /* Intializes random number generator */
+    srand(time(NULL));
+    test();
+    return 0;
+}