C / C++ / MFC

scanf("%d", &t1);
while (t1 > 0){
    printf("%d\n", t1);
    t = t1 % 60;
    t1 = t1 / 60;
    printf("%d : %d\n", t1, t);
    scanf("%d", &t1);
}

// no need for a while loop as you only have a single value to convert
int minutes = t1 % 60; // remainder = 3
int hours = t1 / 60; // 3663 / 60 = 61

#ifdef OS_WINDOWS
# define S7API __stdcall
#else
# define S7API
#endif

1. Use the existing header and source files from the examples and add them to your project. Then call the function using the name and include the header file in the source files where you call it.
   
2. Convert the examples by implementing all the code in Qt classes (source and header).
   

// MainWindow.h
 class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    // No calling convention here because this is a Qt based C++ class member
    void CliCompletion(void *usrPtr, int opCode, int opResult);
    // ...
};

//MainWindow.cpp
#include "snap7.h"
#include "MainWindow.h"
// Other includes

void MainWindow::CliCompletion(void *usrPtr, int opCode, int opResult)
{
    // Call the global implementation from other source file or library
    ::CliCompletion(usrPtr, opCode, opResult);
}

void find_long(char *a)
{
    int l,i,l1=0,j=0,l2=0;
    char b[50],c[50];
    l=strlen(a);
    for (i = 0; i < l; i++) {
        if (a[i] != ' ') {
            b[j] = a[i];
            printf("%c ",b[j]);
            j++;
        }
        else if (a[i] == ' ') {
            b[j] = '\0';
            if (strlen(b) > l1) {
                strcpy(c,b);
                l1 = strlen(b);
            // Inserted missing parentheses here
            }
            j = 0;
        }
        else {
            printf("\nEOF");}
        }
    }
    printf("\nlongest is \n");
    printf(c);
// Added missing parentheses here
}

#include <stdio.h>

enum State
{
  INSIDE_BLANKS,
  INSIDE_WORD
};

void find_longest_word( const char * a, const char ** pps, const char ** ppe);

int main()
{
  const char * foo = "alpha  beta gamma delta epsilon   ";

  const char *ps, *pe;

  find_longest_word( foo, &ps, &pe);

  if ( pe-ps > 0)
  {
    printf("longest word length = %ld\n", (pe-ps));
    while (ps != pe)
    {
      printf("%c", *ps);
      ++ps;
    }
    printf("\n");
  }
  return 0;
}

void find_longest_word( const char * a, const char ** pps, const char **ppe)
{
  const char * ps = a;
  const char * pe = a;
  *pps = *ppe = a;

  enum State state = INSIDE_BLANKS;

  while ( *a != '\0')
  {
    if ( state == INSIDE_BLANKS)
    {
      if ( *a != ' ')
      {
        state = INSIDE_WORD;
        ps = a;
      }
    }
    else // inside word
    {
      if ( *a == ' ')
      {
        pe = a; 
        if ( pe - ps > *ppe - *pps)
        {
          *pps = ps;
          *ppe = pe;
        }
        state = INSIDE_BLANKS;
      }
    }
    ++a;
  }
  // special handling of (possible) last word
  if ( state == INSIDE_WORD)
  {
    if ( pe - ps > *pps - *pps)
    {
      *pps = ps;
      *ppe = pe;
    }
  }
}

const BYTE* pByteArray = reinterpret_cast<const BYTE*>(sSerial.GetString());