Thread: Switch Statement

Hey for my program I am using a switch statement to convert string numbers to int numbers. Its in a function called Set, i'm going to post the whole thing. Its not working it prints out random things and I can't find a pattern to tell whats wrong. I also have another function called Print that prints out the numbers stored in the array and that might be the problem area but I am unsure.

Code:

Set(string num)
{
int i;
if (num[0] == '-')
	{
		positive = false;
		num.erase(0,1);
		numDigits = num.size();
		digits = new int[numDigits];	
		for(i=0;i<numDigits;i++)
		{
			switch (num[i])
			{
				case '0':
					digits[numDigits-i] = 0;
					break;
				case '1':
					digits[numDigits-i] = 1;
					break;
				case '2':
					digits[numDigits-i] = 2;
					break;
				case '3':
					digits[numDigits-i] = 3;
					break;
				case '4':
					digits[numDigits-i] = 4;
					break;
				case '5':
					digits[numDigits-i] = 5;
					break;
				case '6':
					digits[numDigits-i] = 6;
					break;
				case '7':
					digits[numDigits-i] = 7;
					break;
				case '8':
					digits[numDigits-i] = 8;
					break;
				case '9':
					digits[numDigits-i] = 9;
					break;
			}
		}
	}
else
	{
		positive = true;
		numDigits = num.size();
		digits = new int[numDigits];	
		for(i=numDigits;i>=0;i--)
		{
			switch (num[i])
			{
				case '0':
					digits[i] = 0;
					break;
				case '1':
					digits[i] = 1;
					break;
				case '2':
					digits[i] = 2;
					break;
				case '3':
					digits[i] = 3;
					break;
				case '4':
					digits[i] = 4;
					break;
				case '5':
					digits[i] = 5;
					break;
				case '6':
					digits[i] = 6;
					break;
				case '7':
					digits[i] = 7;
					break;
				case '8':
					digits[i] = 8;
					break;
				case '9':
					digits[i] = 9;
					break;
			}
		}
	}
}

>> if(*iter >= 48 && *iter <= 57)
Why use 48 and 57? Just use '0' and '9'. It will work just the same. It will also work for any character set, not just ASCII.

I'm trying to do this without iterators or vectors, just straight arrays and basic stuff.

Originally Posted by DarkDot

I'm trying to do this without iterators or vectors, just straight arrays and basic stuff.

Like this:

Code:

    char myString[] = "-1200";
    signed int number = 0;
    int i;
    int neg = 0;
    
    for (i=0; i < strlen(myString); i++)
    {
        number *=10;
        if (myString[i] == '-' && number == 0)
            neg = !neg;
        else
            if (!neg)
                number += (myString[i] - '0');
            else
                number -= (myString[i] - '0');
    }

I don't understand the above code. I'm going to post my changed code as well as my print function.

Code:

Set(string num)
{
int i;
if (num[0] == '-')
	{
		positive = false;
		num.erase(0,1);
		numDigits = num.size();
		digits = new int[numDigits];	
		for(i=0;i<numDigits;i++)
		{
			digits[i] = num[i]-'0';
		}
	}
else
	{
		positive = true;
		numDigits = num.size();
		digits = new int[numDigits];	
		for(i=numDigits;i>=0;i--)
		{
			digits[i] = num[i]-'0';
		}
	}
}


Print()
{
int i;
if(positive == false)
{
	cout << "-";

	for(i=1;i<=numDigits;i++)
	{
		cout << digits[numDigits-1];
	}
}
else if(positive == true) 
{
	for(i=1;i<=numDigits;i++)
	{
		cout << digits[numDigits-1];
	}
}
}

>> for(i=numDigits;i>=0;i--)
Why does this attempt to go backwards when the other code all goes forward? You are starting one place too early here.

Also, in your Print function you aren't using i at all in the loops, you are just printing the last digit over and over.

i think thats my problem it should print - i not -1