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Cannot enter a newline into a string - please help!

Posted on 2004-10-30
Medium Priority
Last Modified: 2008-02-01

I'm trying to make a procedure where the user will enter a string as a parameter and the "edit box" will display the string on a new line.  It all works except I cannot make the string appear on a new line.  Where the newline should be, a "|" sybol is displayed instead.

Even when I submit the linefeed myself in the paramenter is appears as "|"
e.g. appendText("sometext\n");

Please help

#include <windows.h>
#include <string.h>
#include <stdio.h>
#include <iostream.h>
#include <string>
#include "debug.h"

HWND edit_box = NULL;
#define EDIT_BOX 0x00EB

    switch (iMsg)                                                                  
      case WM_CREATE:                                                            
            RECT rect;

            edit_box = CreateWindow("EDIT",NULL,WS_CHILD | WS_VISIBLE | ES_AUTOHSCROLL |
                                                      ES_AUTOVSCROLL | ES_LEFT | ES_MULTILINE | ES_NOHIDESEL |
                                                      WS_VSCROLL | WS_HSCROLL | WS_BORDER | ES_WANTRETURN,
                                                      0, 0, rect.right, rect.bottom, hwnd, (HMENU)EDIT_BOX,
                                                      ((LPCREATESTRUCT)lParam)->hInstance, NULL);

      case WM_SIZE:                                                break;                                          case WM_PAINT:                                                break;                                          case WM_DESTROY:                                                PostQuitMessage(0);                                                    break;                                          }                                                                              
      return DefWindowProc (hwnd, iMsg, wParam, lParam);            

int debug::debugInit(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow){
      HWND            debug;
      WNDCLASSEX  wndclass;                                                      

    wndclass.cbSize        = sizeof (wndclass);                        
    wndclass.style         = CS_HREDRAW | CS_VREDRAW;            
      wndclass.lpfnWndProc   = WndProc;                                    
    wndclass.cbClsExtra    = 0;                                                
    wndclass.cbWndExtra    = 0;                                                
    wndclass.hInstance     = hInstance;                                    
    wndclass.hIcon         = LoadIcon (NULL, IDI_WINLOGO);      
    wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW);      
    wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH);
    wndclass.lpszMenuName  = NULL;                                          
    wndclass.lpszClassName = "Window Class 1";                                                
    wndclass.hIconSm       = LoadIcon (NULL, IDI_WINLOGO);      

      RegisterClassEx (&wndclass);                                    

      debug = CreateWindow ("Window Class 1",                              
                                     "Game debug",                                

    // check if window creation failed (hwnd would equal NULL)
      if (!debug)
        return 0;
    ShowWindow(debug, nCmdShow);   // display the window
    SetWindowText(edit_box, "yo");

void debug::appendText(char *str){
      char *buff = NULL;
      int length = GetWindowTextLength(edit_box);
      length++; // This accounts for a NULL terminator character

      buff = new char[length];
      GetWindowText(edit_box, buff, length);

      char *finalbuff1  = strcat(buff, "\n");

      char *finalbuff  = strcat(finalbuff1, str);

      SetWindowText(edit_box, finalbuff);

Question by:aspaul
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 12453421
You need:

Author Comment

ID: 12457038
Further to this problem: I added the above code and it works but after a few hundred calls or so the program crashes out and I beleive a problem with resourses causes it.

I added some delete statements as show below:

void debug::appendText(char *str){
      char *buff = NULL;
      int length = GetWindowTextLength(edit_box);
      length++; // This accounts for a NULL terminator character

      buff = new char[length];
      GetWindowText(edit_box, buff, length);

      char *finalbuff1  = strcat(buff, "\r\n");

      char *finalbuff  = strcat(finalbuff1, str);

      SetWindowText(edit_box, finalbuff);

      delete[] buff;
      delete[] finalbuff1;
      delete[] finalbuff;


The problem now is on the first call to this procedure I get this error:

Debug Error!


DAMAGE: after Normal block (#83) at 0x00365988

(press retry to debug the application)

Anyone know why??
LVL 55

Accepted Solution

Jaime Olivares earned 375 total points
ID: 12457084
Your are reserving just space for the null character but not for the appending string, try with this:

void debug::appendText(char *str){
     char *buff;                    // = NULL is not needed;

     int length = GetWindowTextLength(edit_box);
     length += strlen(str)+3; // <-------------This accounts for CR, LF, appending string and  NULL terminator character

     buff = new char[length];
     GetWindowText(edit_box, buff, length);

//     char *finalbuff1  = strcat(buff, "\r\n");     <----- both pointer variables are not needed
//     char *finalbuff  = strcat(finalbuff1, str);
//     SetWindowText(edit_box, finalbuff);
// replace above block with:

     strcat(buff, "\r\n");
     strcat(buff, str);
     SetWindowText(edit_box, buff);

     delete[] buff;

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