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Oct 5th, 2009

Using pointers to strip sentence of spaces

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Hello, this seems like it will be a helpful community. For my degree I need to take a basic C++ class and the only C++ class the offer that fits is an 8 week class, it really goes too fast. Anyways, I've been trying my hardest, but my brain really doesn't think in code, so I've probably made quite a few dumb errors that I can't see.

For this assignment the teacher wants us to write a program that will take an input of a sentence. Then he wants us to pass it to a function that uses pointers to strip the sentence of all spaces. It's really throwing me for a loop, I think I might be on the right track, although it's giving me several compile errors right now. Any help would be greatly appreciated!

C++ Syntax (Toggle Plain Text)
#include <iostream>
using namespace std;
 
void print(char sentence2[],int size);//function to print sentence when done
 
void stripWhite(char point[],char sentence2[],int size);//uses pointers to strip sentence of spaces
 
int main ()
{//main
 
	char sentence1[1000];//first array to obtain sentence
 
	int size;//integer to decide how big new array should be
 
	cout << "Please enter a sentence and I will strip it of all spaces." << endl;
 
	cin >> sentence1;//input for first array
 
	for(int i=0;i<1000;i++)//for loop to find out size of array
	{//for
		if(sentence1[i] >= 'a' && sentence1[i] <= 'z' || sentence1[i] == ' ' || sentence1[i] == ',' || sentence1[i] == '.')
		{//if
			size++;
		}//if
	}//for
 
	char sentence2[size];//new array with exact size it should be
 
	for(int y;y<size;y++)//for loop to copy contents of first array to second
	{//for
		sentence2[y]=sentence1[y];
	}//for
 
	char point;//soon to be pointer
 
	for(int y;y<size;y++)//for loop to get point to become a pointer to second array
	{//for
		point[y]=&sentence2[y];
	}//for
 
	cout << endl;
 
	stripWhite(sentence2,point,size);
 
	return 0;
}//main
 
void print(char sentence2[],int size)//print function
{//void print
 
	for(int z;z<size;z++)
	{//for
		cout << sentence2[z];
	}//for
 
}//void
 
char stripWhite(char point[],char sentence2[],int size)//function to strip sentence of spaces
{//char stripWhite
 
	for(int y;y<size;y++)//for loop to only set non space characters to second array
	{//for
		if(point[y]!=' ')//if to decide if it is a space or not
		{//if
			sentence2[y]=*point[y];
		}//if
	}//for
 
	print(sentence2,size);//function call to print finished sentence
 
}//char
#include <iostream>
using namespace std;

void print(char sentence2[],int size);//function to print sentence when done

void stripWhite(char point[],char sentence2[],int size);//uses pointers to strip sentence of spaces

int main ()
{//main
	
	char sentence1[1000];//first array to obtain sentence
	
	int size;//integer to decide how big new array should be
	
	cout << "Please enter a sentence and I will strip it of all spaces." << endl;
	
	cin >> sentence1;//input for first array
	
	for(int i=0;i<1000;i++)//for loop to find out size of array
	{//for
		if(sentence1[i] >= 'a' && sentence1[i] <= 'z' || sentence1[i] == ' ' || sentence1[i] == ',' || sentence1[i] == '.')
		{//if
			size++;
		}//if
	}//for
	
	char sentence2[size];//new array with exact size it should be
	
	for(int y;y<size;y++)//for loop to copy contents of first array to second
	{//for
		sentence2[y]=sentence1[y];
	}//for
	
	char point;//soon to be pointer
	
	for(int y;y<size;y++)//for loop to get point to become a pointer to second array
	{//for
		point[y]=&sentence2[y];
	}//for
	
	cout << endl;
	
	stripWhite(sentence2,point,size);
	
	return 0;
}//main

void print(char sentence2[],int size)//print function
{//void print
	
	for(int z;z<size;z++)
	{//for
		cout << sentence2[z];
	}//for
	
}//void

char stripWhite(char point[],char sentence2[],int size)//function to strip sentence of spaces
{//char stripWhite
	
	for(int y;y<size;y++)//for loop to only set non space characters to second array
	{//for
		if(point[y]!=' ')//if to decide if it is a space or not
		{//if
			sentence2[y]=*point[y];
		}//if
	}//for

	print(sentence2,size);//function call to print finished sentence
	
}//char

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that_fox

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Oct 5th, 2009

Re: Using pointers to strip sentence of spaces

If this is what you mean.

BTW, where is the pointers.

And a rule of thumb, when you are using char *, instead of string,
you have a bug(In my opinion);

C++ Syntax (Toggle Plain Text)
//str is the string passed. Key is the key that seperates the word
//does not use pointers.
void Strip(std::string str, char key)
{
    string Temp = "";
 
   for(int i = 0; i < str.size(); i++) //Run through the string
    {  
          if(str[i] == key) 
          {
                 // copy str from 0 to i into temp
          }
     }
   return Temp;
}
//str is the string passed. Key is the key that seperates the word
//does not use pointers.
void Strip(std::string str, char key)
{
    string Temp = "";

   for(int i = 0; i < str.size(); i++) //Run through the string
    {  
          if(str[i] == key) 
          {
                 // copy str from 0 to i into temp
          }
     }
   return Temp;
}

firstPerson

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Oct 5th, 2009

Re: Using pointers to strip sentence of spaces

Click to Expand / Collapse Quote originally posted by firstPerson ...

If this is what you mean.

BTW, where is the pointers.

And a rule of thumb, when you are using char *, instead of string,
you have a bug(In my opinion);

I thought that when I put "point[y]=&sentence2[y];" it was getting point to refer to the memory space instead of the value. And then in the stripWhite function "sentence2[y]=*point[y];" was referring to the value within the pointer. Is that not using pointers? I'm sorry to say I'm confused when it comes to pointers. How would I get my program to use pointers if it is not already?

And also, I am not against using strings instead of character arrays, it's just that my professor did not touch on strings much. Although I could use them in this program.

that_fox

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Oct 6th, 2009

Re: Using pointers to strip sentence of spaces

Click to Expand / Collapse Quote originally posted by that_fox ...

I thought that when I put "point[y]=&sentence2[y];" it was getting point to refer to the memory space instead of the value. And then in the stripWhite function "sentence2[y]=*point[y];" was referring to the value within the pointer. Is that not using pointers? I'm sorry to say I'm confused when it comes to pointers. How would I get my program to use pointers if it is not already?

And also, I am not against using strings instead of character arrays, it's just that my professor did not touch on strings much. Although I could use them in this program.

You are close on the "sentence2[y]=*point[y];" part but sentence2[y] must be a pointer. As you have it in your code it is just a plain old variable. The & does return the address of the object, in this case however you cant assign that address to a character. While the compiler might let you do it(if you assign an int to a char it will set the char to be whatever value the char is on the ascii table) I just wrote this little tutorial on pointers. See if it helps. Check the end to see about references.

http://mikectamu.blogspot.com/2009/1...explained.html

As far as the diff between strings and pointer arrays, in C there really is no difference, but in C++ string objects are handled a little differently. A character array can easily be used as a string. I would try to debug your program but since you aren't even using pointers and will have to rewrite it anyways it would seem to be a waste of time. Try rewriting it with the pointers in tact and then if you have problems post it up on here.

Hope that helps!!

chunalt787

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