diff --git a/src/readfloat.c b/src/readfloat.c
--- a/src/readfloat.c
+++ b/src/readfloat.c
-#include <mruby.h>
-
-#ifndef MRB_NO_FLOAT
-/*
- * strtod implementation.
- * author: Yasuhiro Matsumoto (@mattn)
- * license: public domain
- */
-
-/*
-The original code can be found in https://github.com/mattn/strtod
-
-I modified the routine for mruby:
-
- * renamed the function `vim_strtod` -> `mrb_read_float`
- * simplified the code
- * changed the API
-
-My modifications in this file are also placed in the public domain.
-
-Matz (Yukihiro Matsumoto)
-*/
-
-#include <string.h>
-#include <math.h>
-
-MRB_API mrb_bool
-mrb_read_float(const char *str, char **endp, double *fp)
-{
- double d = 0.0;
- int sign;
- int n = 0;
- const char *p, *a;
-
- a = p = str;
- while (ISSPACE(*p))
- p++;
-
- /* decimal part */
- sign = 1;
- if (*p == '-') {
- sign = -1;
- p++;
- }
- else if (*p == '+')
- p++;
- if (ISDIGIT(*p)) {
- d = (double)(*p++ - '0');
- while (*p && ISDIGIT(*p)) {
- d = d * 10.0 + (double)(*p - '0');
- p++;
- n++;
- }
- a = p;
- }
- else if (*p != '.')
- goto done;
- d *= sign;
-
- /* fraction part */
- if (*p == '.') {
- double f = 0.0;
- double base = 0.1;
- p++;
-
- if (ISDIGIT(*p)) {
- while (*p && ISDIGIT(*p)) {
- f += base * (*p - '0') ;
- base /= 10.0;
- p++;
- n++;
- }
- }
- d += f * sign;
- a = p;
- }
-
- /* exponential part */
- if ((*p == 'E') || (*p == 'e')) {
- int e = 0;
-
- p++;
- sign = 1;
- if (*p == '-') {
- sign = -1;
- p++;
- }
- else if (*p == '+')
- p++;
-
- if (ISDIGIT(*p)) {
- while (*p == '0')
- p++;
- if (*p == '\0') --p;
- e = (int)(*p++ - '0');
- for (; *p && ISDIGIT(*p); p++) {
- if (e < 10000)
- e = e * 10 + (*p - '0');
- }
- e *= sign;
- }
- else if (!ISDIGIT(*(a-1))) {
- return FALSE;
- }
- else if (*p == 0)
- goto done;
- d *= pow(10.0, (double)e);
- a = p;
- }
- else if (p > str && !ISDIGIT(*(p-1))) {
- goto done;
- }
-
-done:
- *fp = d;
- if (endp) *endp = (char*)a;
- if (str == a) return FALSE;
- return TRUE;
-}
-#endif
+#include <mruby.h>
+
+#ifndef MRB_NO_FLOAT
+
+#include <string.h>
+#include <math.h>
+
+MRB_API mrb_bool
+mrb_read_float(const char *str, char **endp, double *fp)
+{
+ const char *p = str;
+ const char *a = p;
+ double res = 0.0, frac = 0.0, div = 1.0;
+ int sign = 1;
+ int digits = 0;
+
+ // Skip whitespace
+ while (ISSPACE((unsigned char)*p)) p++;
+
+ // Handle sign
+ if (*p == '-') { sign = -1; p++; }
+ else if (*p == '+') p++;
+
+ // Parse integer part
+ while (ISDIGIT(*p)) {
+ res = res * 10.0 + (*p - '0');
+ digits++;
+ a = ++p;
+ }
+
+ // Parse fractional part
+ if (*p == '.') {
+ p++;
+ while (ISDIGIT(*p)) {
+ frac = frac * 10.0 + (*p++ - '0');
+ div *= 10.0;
+ digits++;
+ }
+ a = p;
+ }
+
+ // If no digits were found, return 0
+ if (digits == 0) {
+ if (endp) *endp = (char*)str;
+ *fp = 0.0;
+ return FALSE;
+ }
+
+ // Combine integer and fractional parts
+ res += frac / div;
+ res *= sign;
+
+ // Handle exponent
+ if ((*p | 32) == 'e') {
+ int e = 0;
+ sign = 1;
+ p++;
+ if (*p == '-') { sign = -1; p++; }
+ else if (*p == '+') p++;
+
+ // If no digits follow 'e', ignore the exponent part
+ if (!ISDIGIT(*p)) goto done;
+
+ while (ISDIGIT(*p)) {
+ if (e < 10000) // 10000 is big enough to get Infinity
+ e = e * 10 + (*p - '0');
+ p++;
+ }
+ res *= pow(10.0, sign * e);
+ a = p;
+ }
+
+ // Set endp
+ done:
+ if (endp) *endp = (char*)a;
+ *fp = res;
+
+ // strtod(3) stores ERANGE to errno for overflow/underflow
+ // mruby does not require those checks
+#if 0
+ // Check for underflow after applying the exponent
+ if (res != 0.0 && fabs(res) < DBL_MIN) {
+ return FALSE;
+ }
+
+ // Check if the result is infinity or NaN
+ if (isinf(res) || isnan(res)) {
+ return FALSE;
+ }
+#endif
+ return TRUE;
+}
+
+#endif