C / C++ / MFC

#include <string.h>

int Parse(char *String)
{
	int Temp = 0;
	int Result = 0;
	int Length = int(strlen(String)); // The length of the string.
	bool Negative = false;
	// Main cycle. Loop through all the symbols of the string.
	for (int i = 0; i < Length; i++)
	{
		if (i = 0)
		{
			// If the first symbol of the string is "-". Make it negative.
			if (String[i] == 45)
			{
				Negative = true;
			}
		}
		else
		{
			// Make sure the input symbol is a number. Return 0 if it's not.
			if (String[i] < 48)
			{
				return 0;
			}
			else if (String[i] > 57)
			{
				return 0;
			}
			else
			{
				// For aech number, perform specific operations.
				switch (String[i])
				{
					// If it's 0.
				case 48:
					Temp = 1;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 1.
				case 49:
					Temp = 1;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 2.
				case 50:
					Temp = 2;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 3.
				case 51:
					Temp = 3;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 4.
				case 52:
					Temp = 4;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 5.
				case 53:
					Temp = 5;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 6.
				case 54:
					Temp = 6;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 7.
				case 55:
					Temp = 7;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 8.
				case 56:
					Temp = 8;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
					// If it's 9.
				case 57:
					Temp = 9;
					for (int j = 0; j < (Length - i); j++)
					{
						Temp *= 10;
					}
					Result += Temp;
					Temp = 0;
					break;
				}
			}
		}
	}
	if (Negative == true)
	{
		Result = Result - (Result * 2);
	}
	return Result;
}