Add handling of double values with just integer part

Author: josesimoes

src/CLR/Helpers/nanoprintf/nanoprintf.c

@@ -1,4 +1,4 @@
-//
+//
 // Copyright (c) .NET Foundation and Contributors
 // Portions Copyright (c) 2006 - 2021 Skirrid Systems. All rights reserved.
 // See LICENSE file in the project root for full license information.
@@ -93,7 +93,7 @@ Floating point
   #define DP_LIMIT      310
   #define MAX_POWER     256
 // [NF_CHANGE]
-  #define FLOAT_DIGITS  18
+  #define FLOAT_DIGITS  19
 // [END_NF_CHANGE]
 #else
   #define DP_LIMIT      40
@@ -147,6 +147,31 @@ static char *trim_zeros(char *p)
     return p;
 }
 
+// [NF_CHANGE]
+
+flt_width_t count_integer_digits(double number) {
+    // Handle negative numbers
+    if (number < 0) {
+        number = -number;
+    }
+
+    // Handle special case for zero
+    if (number < 1.0) {
+        return 1;
+    }
+
+    flt_width_t count = 0;
+
+    while (number >= 1.0) {
+        number /= 10.0;
+        count++;
+    }
+
+    return count;
+}
+
+// [END_NF_CHANGE]
+
 /* ---------------------------------------------------------------------------
 Function: format_float()
 Called from the main doprnt function to handle formatting of floating point
@@ -271,6 +296,21 @@ static char *format_float(double number, flt_width_t ndigits, flt_width_t width,
              * to the answer in the fastest time, with the minimum number of
              * operations to introduce rounding errors.
              */
+
+            // [NF_CHANGE]
+
+            // check if number is integer
+            if (number == (int)number)
+            {
+                // number is an integer
+
+                // set number of digits required to have 0 decimal places
+                ndigits = count_integer_digits(number);
+            }
+
+            // [END_NF_CHANGE]
+
+            // Normalise the number such that it lies in the range 1 <= n < 10.
             // First make small numbers bigger.
 
             i = 0;