simple text_to_number function

// A few issues ...
//
// 1. Use of `pow` here isn't warranted -- it adds slowness and imprecision.
//
// 2. `search_first_character_in_text` could be replaced by `strchr`. It is
// called twice. But, could be eliminated.
//
// 3. `char_to_digit` should return `int`. It could also be simplified.
// But it could/should be eliminated.
//
// 4. The `template` has `typename number` but `number` isn't used.
//
// 5. Not really a good candidate for a `template`
//
// 6. No error checking
//
// 7. No real need to pass the string length. A running check for EOS (0x00)
// is sufficient (faster).
//
// Unfortunately, I had to completely restructure your code.

#include <stdio.h>
#include <stdlib.h>

double
text_to_number(const char *text,int *erroff)
{
	const char *cur = text++;
	int chr;
	int neg = 0;
	int gotdot = 0;
	int fractional_div = 1.0;
	double converted_number = 0.0;

	// NOTE: replace the error handling with whatever you'd like (e.g. throw)
	*erroff = -1;

	// assume number is (of the form):
	//   -34531.742

	// handle negative sign
	chr = *cur;
	if (chr == '-') {
		neg = 1;
		++cur;
	}

	for (chr = *cur++;  chr != 0;  chr = *cur++) {
		// look for the "."
		if (chr == '.') {
			// we got: 123.45.6
			if (gotdot) {
				*erroff = cur - text;
				break;
			}
			gotdot = 1;
			continue;
		}

		// valid digit
		if ((chr >= '0') && (chr <= '9')) {
			// get the value
			double dig = chr - '0';

			// convert fractional part:
			//   7 --> 0.7
			//   4 --> 0.04
			//   2 --> 0.002
			if (gotdot) {
				fractional_div *= 10.0;
				dig /= fractional_div;
			}

			// convert main part
			else
				converted_number *= 10.0;

			// add in the digit
			converted_number += dig;

			continue;
		}

		// invalid syntax
		*erroff = cur - text;
		break;
	}

	// apply sign
	if (neg)
		converted_number = -converted_number;

	return converted_number;
}

void
test(const char *text)
{
	int erroff;
	double ret = text_to_number(text,&erroff);

	printf("'%s' --> %.15g",text,ret);

	if (erroff >= 0) {
		text += erroff;
		printf(" ERROR: '%s'",text);
	}

	printf("\n");
}

int
main(void)
{

	test("34531.742");
	test("-34531.742");
	test("-34531.7426821");
	test("-345.31.7426821");
	test("-34531.7426-821");

	return 0;
}