Okay, I'm trying to learn how to use scroll bars in windows, and I thought it would be easy to just read in some text file and display it in my window instead of creating a bunch text in the source code. Well, the code doesn't seem to work. What I wanted it to do was open a file and first scan through it and get the number of lines and the length of the largest line. Next, store the text in a dynamicaly allocated 2-dim array, and put it on the screen. I've created a few functions for this. They are:
void **Create_Array(int iSize, int iNumLines, int iLineWidth)
- allocates memory for array.
void Delete_Array(void **array, int iNumLines)
- deletes a 2-dim array
int Scan_File(FILE *file, int *iNumLines, *iLineWidth)
- counts the number of lines and max line width
One thing I couldn't figure out was why I couldn't use the increment operator(++) for *iNumLines and *iLineWidth in Scan_File(). *iNumLines++ does not work. It just returns 0. So instead I just used two other variables and stored their final values in iNumLines and iLineWidth, and that did work.
Anyway, instead of printing text to the window it just prints one line of random text on the screen and then the rest of the lines are some other character. It looks something like this:
Sample line five ..ine ree.
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXX
Where line one is a composition of the last line and the two lines preceeding it. I tried testing the code in a console window instead and it does display the text properly, but after each line there are four characters which are the ascii(253) "square" symbol.
If I had to guess I'd say it has something to do with the way the array was created, but I really don't know.
Heres the code. Sorry it's so long. I tried to clean it up a bit.
main1.c
lib1.cCode:#include <windows.h> #include <stdio.h> #include <stdlib.h> #include "mylib.h" LRESULT CALLBACK WndProc( HWND, UINT, WPARAM, LPARAM); int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT("insert name here") ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW|CS_VREDRAW ; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION) ; wndclass.hCursor = LoadCursor(NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName = szAppName ; if(!RegisterClass(&wndclass)) { MessageBox(NULL,TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow(szAppName, TEXT("program name here"), WS_OVERLAPPEDWINDOW|WS_VSCROLL, CW_USEDEFAULT,CW_USEDEFAULT, CW_USEDEFAULT,CW_USEDEFAULT, NULL,NULL,hInstance, NULL) ; ShowWindow(hwnd, iCmdShow) ; UpdateWindow(hwnd) ; while(GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg) ; DispatchMessage(&msg) ; } return msg.wParam ; } LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { HDC hdc ; PAINTSTRUCT ps ; TEXTMETRIC tm ; static FILE *myfile ; static char **my_array ; static int cyChar,cxChar,iNumLines,iLineWidth, error ; int ch = 0 ; int row = 0 ; int col = 0 ; switch(message) { case WM_CREATE: hdc = GetDC(hwnd) ; GetTextMetrics(hdc,&tm) ; cxChar = tm.tmAveCharWidth ; cyChar = tm.tmHeight + tm.tmExternalLeading ; ReleaseDC(hwnd,hdc) ; if((myfile = fopen("test.txt","r")) == NULL) { error = -1 ; } else { if((Scan_File(myfile,&iNumLines,&iLineWidth)) != DONE) error = -1 ; if((my_array = (char **) Create_Array(sizeof(char),iNumLines,(iLineWidth + 1))) == NULL) error = -1 ; if(my_array == NULL) error = -1 ; if(iNumLines <= 0) error = -1 ; else { //Now that array is created. Read text into array for(row = 0, col = 0 ; row < iNumLines; row++) { while((ch = fgetc(myfile)) != EOF) { switch(ch) { case '\n': col = 0 ; break ; default: my_array[row][col] = (char) ch ; col++ ; break ; } } if(ch == EOF) //This shouldn't happen row = (iNumLines - 1) ; } } } break ; case WM_PAINT: hdc = BeginPaint(hwnd,&ps) ; if(error == -1) { TextOut(hdc,0,0,"Could not open file",sizeof("Could not open file")) ; } else { for(row = 0 ; row < iNumLines ; row++) { TextOut(hdc,0,(cyChar * row),my_array[row],iLineWidth) ; } } EndPaint(hwnd,&ps) ; break ; case WM_DESTROY: Delete_Array(my_array,iNumLines) ; if(error != -1) fclose(myfile) ; PostQuitMessage(0) ; break ; } return DefWindowProc(hwnd,message,wParam,lParam) ; }
mylib.hCode:#include <stdio.h> #include <stdlib.h> #include "mylib.h" void **Create_Array(int size,int rows, int cols) { void **array ; int x = 0 ; if((array = (void **) calloc(rows,size)) == NULL) return NULL ; for(x = 0 ; x < rows ; x++) if((array[x] = (void *) calloc(cols,size)) == NULL) return NULL ; return array ; } void Delete_Array(void **array, int rows) { int x = 0 ; for(x = 0 ; x < rows ; x++) free(array[x]) ; } int Scan_File(FILE *file,int *iNumLines, int *iLineWidth) { int iCharCount = 0 ; int ctr = 0 ; int iLineCtr = 0 ; int ch = ' ' ; //check to see if the file is open if(file == NULL) return FILE_NOT_OPEN ; else { while((ch = fgetc(file)) != EOF) { if(ch == '\n') { if(iCharCount > *iLineWidth) *iLineWidth = iCharCount ; iCharCount = 0 ; iLineCtr++ ; } else { iCharCount++ ; } } *iNumLines = iLineCtr ; rewind(file) ; } return DONE ; }
I appreciatte any help, thanks.Code:#ifndef _MYLIB_H_ #define FILE_NOT_OPEN 1 #define DONE 2 void **Create_Array(int size,int rows, int cols) ; void Delete_Array(void **array, int rows) ; int Scan_File(FILE *file,int *iNumLines, int *iLineWidth) ; #endif
