Comparing String Question

Sorry if I sound like an idoit, but when I call a function that puts information into a buffer, such as Process32First, Why is it that when I compare it somthing like "Explorer.exe" it doesnt work? Ive checked the buffer, pe32.szExeFile, and its prints "Explorer.exe". Is there something appended to the end? Is there a trim function like in VB? Im just a bit conufsed, Im more experienced in VB but Im moving on to C++.

Can you post a short example of the code that shows us how you are trying to do the comparison?

How are doing the comparison and what exactly are you comparing? Is it a C-style char array or a C++ string container? Are you using the equality operator ==? Let me take a guess and say you are using C-style char arrays and the equality operator.

Code:

---

char buffer[] = "Explorer.exe"
...
if( buffer == "Explorer.exe" )
{
    // They are equal, do something
}

---

The reason that does not work is that both the array name (the part in blue) and the string literal (the part in red) are interpreted as addresses by the compiler in the code above. The if statement above is essentially seen as:

Code:

---

if( address of buffer == address of string literal "Explorer.exe" )

---

The addresses of these two things are NEVER going to be equal. The compiler will allocate different memory addresses to them.

If you want to compare these you need to use the strcmp function:

Code:

---

char buffer[] = "Explorer.exe";
...
if( strcmp(buffer,"Explorer.exe") == 0 )
{
    // They are equal, do something
}

---

Or, you can just use a C++ string container which has an overloaded == operator and can correctly handle this case:

Code:

---

string buffer = "Explorer.exe";
...
if( buffer == "Explorer.exe" )
{
    // They are equal, do something
}

---

here is an example

Code:

---


  // Set the size of the structure before using it.
  pe32.dwSize = sizeof( PROCESSENTRY32 );

  // Retrieve information about the first process,
  // and exit if unsuccessful
  if( !Process32First( hProcessSnap, &pe32 ) )
  {
    printError( "Process32First" );  // Show cause of failure
    CloseHandle( hProcessSnap );    // Must clean up the snapshot object!
    return( FALSE );
  }

    if (pe32.szExeFile=="Explorer.exe")    <---------- HERE
    {
        printf("\n FOUND!!!!!!!!!!!!!!");
        }

---

EDIT: StrCmp worked. Thanks :)

Not sure if it makes a difference, but the buffer in the structure is of type TCHAR, so he should probably use the _tcscmp function instead, and the _T() macro for string literals.

Code:

---

if (_tcscmp(pe32.szExeFile,_T("Explorer.exe")) == 0) {
    // equal, do whatever
}

---