How do I remove a character from character array?

I am tryin gto make a program that allows the user to enter a string as a character array and a letter to delete from the array. I am having a very hard time deleting the letter from the array. The word can not have a space where the letter used to be. So if the user enters "hello world" and the letter 'l'. It should print "heo word". Can someone please point me in the right direction here? Thanks

Code:

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#include<iostream>
using namespace std;
int main()
{
        void remove(char[], char);
        char letter ;
        const int MAX = 55;
        char cstring[MAX];

        cout << "Enter sentence and a letter will be removed\n";

        cin.getline(cstring, MAX);

        cout << "Enter letter to be removed";
        letter = cin.get();

        remove(cstring, letter);

        cout << cstring << endl;

        cin.ignore();
       

        return 0;
}

void remove(char cstring[], char letter)
{
        char temp;
       
       
        for(int i = 0; cstring[i] != '\0'; i++)
        {

                if(cstring[i] == letter) cstring[i] =               
                       
        }

       
}

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You can't just "remove", you also have to "paper over the hole" by moving other letters over to the left to take their place. (And yes, you'll have to move the whole rest of the string down.)

I got it to work like this

Code:

---

void remove(char cstring[], char letter)
{
        char cstring2[55];
       
        for(int i = 0; cstring[i] != '\0'; i++)
        {

        if(cstring[i] != letter)  cout << cstring[i];       
                       
        }

       
}

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But I need to print the string in main, not in the remove() function. So I was thinking of using strcpy, to try and copy all letters except the specified letter into a new character array. Is this possible? I looked up strcpy and found no one is using it like I'm trying to, but maybe there is good reason for that? :)

As I recall, you can't use strcpy on "overlapping" things (i.e, if the source and destination are in the same place in memory). memmove might work in that respect. I would still suggest shifting the whole thing over yourself, though.

Can you give me some idea how to do that?

If you have to delete character 4:
Put character 5 in the 4th spot.
Put character 6 in the 5th spot.
Put character 7 in the 6th spot.
Put character 8 in the 7th spot.
.
.
.
Put character (last) in the (last-1)th spot.

Presumably you'll do that in a loop. Since it's a string, once you reach the \0 character you are done.

Quote:

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Originally Posted by tabstop

If you have to delete character 4:
Put character 5 in the 4th spot.
Put character 6 in the 5th spot.
Put character 7 in the 6th spot.
Put character 8 in the 7th spot.
.
.
.
Put character (last) in the (last-1)th spot.

Presumably you'll do that in a loop. Since it's a string, once you reach the \0 character you are done.

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This will work with the way my program is set up now? Also, this will work if I have to delete character 4, 5, and 11?

Quote:

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Originally Posted by nick753

This will work with the way my program is set up now? Also, this will work if I have to delete character 4, 5, and 11?

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As long as you're using C-style strings (arrays of char with \0 at the end), then it will work wonderfully. If you have to delete multiple things, you do it multiple times.

should I set last to strlen? Like this

last = strlen(cstring)

??

Why don't you implement the whole algorithm and if it breaks then we'll fix it. Whether something like that is correct depends on what happens.

That will certainly give you the right number.

Quote:

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Originally Posted by whiteflags

Why don't you implement the whole algorithm and if it breaks then we'll fix it. Whether something like that is correct depends on what happens.

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I have been trying to create an algorithm for about 3 hours now and nothing I do works. I don't know what to do.

Isn't there a way that I can store all of the letters that are != to letter into another char array? That is what I was hoping to do with strcpy.

I am pointing out that you ought to post some code instead of asking questions about a random statement you think could be right or wrong. If you seriously have no idea what to do, then you haven't been paying attention, either. Try writing what you think you should do, based on what you've been told, because to be honest, it's very hard to show you more of the algorithm without giving you an implementation.

Quote:

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Isn't there a way that I can store all of the letters that are != to letter into another char array? That is what I was hoping to do with strcpy.

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If you find all the instances of letter, then that should break up the cstring into sections that you can copy to another destination (as in, not cstring) with strncpy.

Here is my attempt at doing that, but it is giving me spaces where the letter used to be when I cout the 2nd array.

Code:

---

        for(int i = 0; cstring[i] != '\0'; i++)
        {
            if(cstring[i] != letter)
            {
            cstring2[i] = cstring[i];           
           
            }
 
              cout << cstring2[i];
    }

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Yes those are places left by characters that you 'removed'. You will have to replace them with their neighbors.

By replacing them with their neighbors you mean pushing back all the characters after the space that were left? And I would do this with the 2nd char array?

Yes that is exactly what I mean. If you know exactly where you want to copy the next valid character though, then that would avoid the problem.

How would I copy the next valid character to a specific spot?

Keep track of the spot.

I just can't get it, how can I push back all of the characters after the space of the removed characters? I tried finding it in my book, and there is nothing like that. I tried looking online and can't find anything that relates to this. I've never done this before, I'm stuck!

Quote:

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Originally Posted by nick753

I've never done this before, I'm stuck!

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1) This is a bad attitude to have: at every point in your career, you will almost always be doing something you haven't done before. (If you had done it before, you'd just reuse the code and there you are.)

2) Have you read any posts in the thread other than your own? We've been pretty explicit on how to do this. You know where to start replacing, because that's where you found your letter. Every character after that, you need to move forward one space. So, do that.

Quote:

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Originally Posted by tabstop

1) This is a bad attitude to have: at every point in your career, you will almost always be doing something you haven't done before. (If you had done it before, you'd just reuse the code and there you are.)

2) Have you read any posts in the thread other than your own? We've been pretty explicit on how to do this. You know where to start replacing, because that's where you found your letter. Every character after that, you need to move forward one space. So, do that.

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I think my version is much easier, thanks for trying to help though!

Code:

---

void remove(char cstring[], char letter)
{
int j = 0;
int i ;

for( i = 0; cstring[i] != '\0'; i++ )
{
cstring[j] = cstring[i];


if(cstring[i] != letter)
++j;       

}       
// terminate j
cstring[j] = '\0';
}

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Good, but you should indent your code properly:

Code:

---

void remove(char cstring[], char letter)
{
    int j = 0;

    for (int i = 0; cstring[i] != '\0'; ++i)
    {
        cstring[j] = cstring[i];

        if (cstring[i] != letter)
            ++j;
    }

    // terminate j
    cstring[j] = '\0';
}

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Since i is only in the scope of the for loop, I have moved it to be local to the for loop. Finally, if you actually had to do this other than in an exercise, an appropriate solution would be to use a std::string, and then write:

Code:

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str.erase(std::remove(str.begin(), str.end(), 'l'), str.end());

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Code:

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void remove(char* input, char ch)
{
    char* output = input;
    while (*input)
    {
        if (*input != ch)
        {
            *(output++) = *input;
        }
        ++input;
    }
    *output = 0;
}

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Haven't read the replies.

Quote:

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Originally Posted by kmdv

Haven't read the replies.

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If you did you would have seen that your algorithm is essentially the same as the one nick753 implemented and posted in post #23.