Der Code:

sort.cpp

#include "sort.h"

bool Sort::IsInteger(char c)
{
	switch (c)
	{
	case 0:
	case 1:
	case 2:
	case 3:
	case 4:
	case 5:
	case 6:
	case 7:
	case 8:
	case 9:
		return true;
		break;
	default: 
		return false;
		break;
	}
}

int Sort::WhatInteger(char c)
{
	switch (c)
	{
	case 0:
		return 0;
		break;
	case 1:
		return 1;
		break;
	case 2:
		return 2;
		break;
	case 3:
		return 3;
		break;
	case 4:
		return 4;
		break;
	case 5:
		return 5;
		break;
	case 6:
		return 6;
		break;
	case 7:
		return 7;
		break;
	case 8:
		return 8;
		break;
	case 9:
		return 9;
		break;
	default:
		return 0;
		break;
	}
}

void Sort::SortCharToInteger(char* c_source, int* i_destination)
{
	char c_sort;
	char* c_point;

	c_point = 0;

	for (int i = 0; c_source[i] != '\0'; i++)
	{
		c_point = &c_sort;
		*c_point = c_source[i];

		if (IsInteger(c_sort) == true)
		{
			i_destination += WhatInteger(c_sort);
		}
	}
}

sort.h

#pragma once

#include "stdafx.h"

class Sort
{
public:
	bool IsInteger(char c);
	int WhatInteger(char c);
	void SortCharToInteger(char* c_source, int* i_destination);

private:
};

{//besser wäre "int Sort::SortCharToInteger(const char* c_source)"

FTFY