Read an UDT data file in VC++

[Chris]

I know how to do this in VB. But can anyone teach me how to archieve this in VC++?

Option Explicit
Private Type sData
    ID As String
    Age As Integer
    Name As String
End If
Private sd As sData

Private Sub ReadFile()
Dim Ptr As Long

    Open "C:\1.dat" For Binary As #1
        Ptr = 0
        Do While Not EOF(1)
            Get #1, (Ptr * Len(sd)) + 1, sd
            Debug.Print sd.ID
            Debug.Print sd.Age
            Debug.Print sd.Name
            
            Ptr = Ptr + 1
            DoEvents
        Loop
    Close #1
End Sub

[parksie]

Something like this:

#include <stdio.h>

struct MyType {
    int iNum;
    bool bX;
};

void main() {
    FILE *pFile = fopen("temp.dat", "wb");
    MyType X = {5, true};
    MyType Y;

    fwrite(pFile, &X, sizeof(MyType);
    fclose(pFile);

    pFile = fopen("temp.dat", "rb");
    fread(pFile, &Y, sizeof(MyType);

    fclose(pFile);

    printf("%d = %d", iNum, bX);
}

[Chris]

Parksie, can it be done by using the ReadFile API function? and use pointer to read various section of the file?

[Chris]

Parksie, When I run your code, I get some error and later on I modified the here and there and it work now.

'//Code in MyProject.h
void ReadWrite(HWND);

typedef struct {
	int iNum;
	bool bX;
}MyType;
MyType X;
MyType Y;

'//Code in MyProject.cpp
void ReadWrite(HWND hDlg)
{
    FILE *pFile = fopen("c:\\1.dat", "wb");
    X.bX = true;
	X.iNum = 5;

    fwrite(&X, sizeof(MyType), sizeof(MyType), pFile);
    fclose(pFile);

    pFile = fopen("C:\\1.dat", "rb");
    fread(&Y, sizeof(MyType), sizeof(MyType), pFile);

    fclose(pFile);

    printf("%d = %d", Y.iNum, Y.bX);
	return;
}

Do you have any idea on how to read the file by a given address location?

[Chris]

Parksie, I found that I can use the SetFilePointer API to move the open file pointer to the location I need. But Do you know how to use the OpenFile API to open a Binary file?

Thx

[Chris]

can someone explain this to me?

typedef struct {
    long ID;
    float fees;
    double pt;
} TEST;
TEST ut;

void ReadWrite(HWND hDlg)
{
    FILE *pFile;
    //Open the map data file
    pFile = fopen("C:\\2.dat", "rb");

    //Read the Genral Information abt the Map data file
    fread(&ut, sizeof(ut), 1, pFile);

    //Close the Map data file
    fclose(pFile);

    return;
}

if I include the extra element call Name then I will not be able to read the data correctly from a binary file as I read with the above method.

typedef struct {
    char Name[5];
    long ID;
    float fees;
    double pt;
} TEST;
TEST ut;

void ReadWrite(HWND hDlg)
{
    FILE *pFile;
    //Open the map data file
    pFile = fopen("C:\\2.dat", "rb");

    //Read the Genral Information abt the Map data file
    fread(&ut, sizeof(ut), 1, pFile);

    //Close the Map data file
    fclose(pFile);

    return;
}

But If i resort the structure as below, I'll be able to read the data correctly from a binary file

typedef struct {
    long ID;
    float fees;
    double pt;
    char Name[5];
} TEST;
TEST ut;

void ReadWrite(HWND hDlg)
{
    FILE *pFile;
    //Open the map data file
    pFile = fopen("C:\\2.dat", "rb");

    //Read the Genral Information abt the Map data file
    fread(&ut, sizeof(ut), 1, pFile);

    //Close the Map data file
    fclose(pFile);

    return;
}