Word Wrap Function

[Mary Magdalene]

Hi all, I wanted to practice my beginner skills with a little text game, but I want a word wrap function to format the text properly. I found this one that looks promising, but I can't figure out how to use it.

/*
   This function takes a string and an output buffer and a desired width. It then copies
   the string to the buffer, inserting a new line character when a certain line
   length is reached.  If the end of the line is in the middle of a word, it will
   backtrack along the string until white space is found.
 */
 
#include <string.h>
#include <ctype.h>
 
char* word_wrap (char* buffer, char* string, int line_width) {
    int i = 0;
    int k, counter;
 
    while(i < strlen( string ) )
    {
        // copy string until the end of the line is reached
        for ( counter = 1; counter <= line_width; counter++ )
        {
            // check if end of string reached
            if ( i == strlen( string ) )
            {
                buffer[ i ] = 0;
                return buffer;
            }
            buffer[ i ] = string[ i ];
            // check for newlines embedded in the original input
            // and reset the index
            if ( buffer[ i ] == '\n' )
            {
                counter = 1;
            }
            i++;
        }
        // check for whitespace
        if ( isspace( string[ i ] ) )
        {
            buffer[i] = '\n';
            i++;
        }
        else
        {
            // check for nearest whitespace back in string
            for ( k = i; k > 0; k--)
            {
                if ( isspace( string[ k ] ) )
                {
                    buffer[ k ] = '\n';
                    // set string index back to character after this one
                    i = k + 1;
                    break;
                }
            }
        }
    }
    buffer[ i ] = 0;
 
    return buffer;

Can anyone tell me the correct usage for this code? I'm not sure what "buffer" is supposed to be when calling the function.

[coder777]

buffer is the result (it's also the returned value). Make buffer at least the the size of string

[Mary Magdalene]

Hi coder777, thanks for the reply. Could you give an example of the function in use?

Like word_wrap(x, "blah blah blah", 80)?

[TwilightSpectre]

1 2 3 4 5 6 7 8 9 10 11 12 13 14

#include <stdio.h> // your function int main(void) { // example message const char* message = "Testing 1 2 3 4 This is a message"; // buffer for storing the resultant string - make sure its large enough! char buffer[40] = {0}; printf("Message:\n%s\n", word_wrap(buffer, message, 15)); return 0; }

Message: Testing 1 2 3 4 This is a message

Note that you should really change the second parameter to take const char* rather than char* - otherwise the above example (shouldn't) compile due to the casting away of qualifiers.

[Mary Magdalene]

Ahh wonderful! Thank you so much for the help!

[Mary Magdalene]

Shoot, I forgot to ask something. How would this work when using variables mid-sentence?

Example:

const char* room1 = "Your name is " player_name " and you're super kewl!"

Obviously this doesn't work. Would I have to just keep making new sentence variables for each variable that breaks a sentence?

[TwilightSpectre]

Are you using C++ or C?
If you are using C++, its quite easy. Just use a std::string, and you can add variables to it, or you could use std::stringstream:

std::string room1 = "Your name is" + std::string(player_name) + " and you're super kewl!";
word_wrap(buffer, room1.c_str(), 20);

If you are using C, you should instead use snprintf, like this:

char message[256];
snprintf(message, 255, "Your name is %s and you're super kewl!", player_name);

[Mary Magdalene]

Hi, I hate to bother you about this again, but I can't get the + operators to work. For example:

char buffer[3000] = {0};

const char* finalize = "Your name is " + string(player_name) + " and you're " + string(age) + " years old. You're a " + string(gender) + " and your body type is " + int(body) + ".";

cout << (word_wrap(buffer, finalize, 80);

Trying to use this spits out the following error:
error: no match for 'operator+' (operand types are 'std::basic_string<char>' and 'int')

Any ideas? I tried using finalize.c_str() as well, same error... can't get this working.

[TwilightSpectre]

You are using char arrays, rather than std::string. I'm going to assume you are using C++ (from your error message). You need to use the to_string function to convert:

#include <string>
//...

char buffer[3000] = {0};
/* Assuming:
std::string player_name;
int age;
std::string gender;
std::string body;
*/

std::string finalize = "Your name is " + player_name + " and you're " + std::to_string(age) + 
                       " years old. You're a " + gender + " and your body type is " + body + ".";
word_wrap(buffer, finalize.c_str(), 80);
cout << buffer << '\n';

You'll also need to have a compiler with C++11 - VS is enable by default, for GCC or Clang you'll need to add it yourself (normally with -std=c++11).

[Mary Magdalene]

I really appreciate your help, but I still can't get it to work even when copy/pasting verbatim. I'm going to post the entire code so far, maybe you could figure out what's wrong? I'm getting "to string is not a member of std." C++11 is enabled. Also, in this case age is handled as a string, and body is an int. When removing to_string and putting age as just "age", I get the same operator+ error from before.

http://pastebin.com/e2v4pP1v

[long double main]

Some compilers don't have the std::to_string function implemented yet for certain systems.

You can just make your own to_string function if you think you're running one of those:

// You'll need to #include <sstream>
// Just stick this at the top somewhere...
template <typename T>
std::string to_string(const T& x)
{
    std::ostringstream oss;
    oss << x;
    return oss.str();
}

(If you end up using this one, make sure you don't use std:: when you call it)

[Mary Magdalene]

Excellent! The manual to_string function fixed everything. Once again, thank you guys for the help and education!

[Mary Magdalene]

Well... I'm unfortunately back again. I seem to have a never ending supply of problems getting this code to work the way I want it to. Here's the problem now:

//Finalize character.
    char finalize_B[3000] = {0};
    std::string finalize_S = "Your name is " + player_name + " and you're " + age + " years old. You're a " + gender + " and your body type is ";
    word_wrap(finalize_B, finalize_S.c_str(), 80);
    cout << endl << finalize_S;
    if (body == 1)
    {
        char finalizewhale_B[3000] = {0};
        string finalizewhale_S = "fat and blubbery.";
        word_wrap(finalizewhale_B, finalizewhale_S.c_str(), 80);
        cout << finalizewhale_S << endl;
    }
    else if (body == 2)
    {
        char finalizeburly_B[3000] = {0};
        string finalizeburly_S = "burly and strong.";
        word_wrap(finalizeburly_B, finalizeburly_S.c_str(), 80);
        cout << finalizeburly_S << endl;
    }

Using the function inside of if checks to append additional strings breaks the ability to word wrap. Does anyone know if this is easily fixable?

[Mary Magdalene]

Bump. :(

[cire]

You could go for a more C++-ish approach and avoid the raw character arrays altogether.

#include <iostream>
#include <string>
#include <cctype>

std::string word_wrap(std::string text, unsigned per_line)
{
    unsigned line_begin = 0;

    while (line_begin < text.size())
    {
        const unsigned ideal_end = line_begin + per_line ;
        unsigned line_end = ideal_end <= text.size() ? ideal_end : text.size()-1;

        if (line_end == text.size() - 1)
            ++line_end;
        else if (std::isspace(text[line_end]))
        {
            text[line_end] = '\n';
            ++line_end;
        }
        else    // backtrack
        {
            unsigned end = line_end;
            while ( end > line_begin && !std::isspace(text[end]))
                --end;

            if (end != line_begin)                  
            {                                       
                line_end = end;                     
                text[line_end++] = '\n';            
            }                                       
            else                                    
                text.insert(line_end++, 1, '\n');
        }

        line_begin = line_end;
    }

    return text;
}

int main()
{
    std::string player_name = "Eric";
    std::string age = "152";
    std::string gender = "transgender";

    enum body_type { fit, unfit };
    body_type body = fit;

    std::string working_text = "Your name is " + player_name + " and you're " + age + " years old. You're a " + gender + " and your body type is ";

    std::cout << word_wrap(working_text, 10) << "\n\n" ;
    std::cout << word_wrap(working_text + (body == fit ? "burly and strong." : "fat and blubbery."), 10) << '\n';
}

http://ideone.com/wai9da


[Edit: Note that there is a bug in the code as originally posted -- corrected now.]

[coder777]

So why cout << endl << finalize_S;? I'd expect that it'd be _B

On line 9/16 you do not append. To append you need to do this:

string finalizewhale_S = finalize_S + "fat and blubbery."

[Mary Magdalene]

Hi coder777, I tried your method, but it breaks the wordwrapping of finalize_S, and only applies the word wrap to the "fat and blubbery" part.

I think I give up on this word wrap... for such a simple thing it feels like rocket science to a beginner like me and it's way more frustration than it's worth. I'm going to try cire's wordwrap function later, hopefully it'll work the way I want it to, otherwise I give up.

Thanks everyone for all the time you took to help, I really appreciate it.

[cire]

Looking at it now, there's still an error in the code. The <= on line 12 should just be <.