Dev C++ Func Problem

I'm using Dev-C++ and I tried to compile the below code:

Code:

#include <iostream>

using namespace std;

int validnum(int lower,int higher);

int main()
{
    cout << "Please enter your birthday. Enter the year: ";
    int year = validnum(1990,1998);
    cout << "Enter the month: ";
    int month = validnum(1,12);
    int date = 0;
    switch(month)
    {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
                date = validnum(1,31);
                break;
        case 4:
        case 6:
        case 9:
        case 11:
                date = validnum(1,30);
                break;
        case 2:
                if (year%4 == 0)
                {
                     date = validnum(1,29);
                     break;
                }
                else
                {
                     date = validnum(1,28);
                     break;
                }
    }
    
    cout << endl
         << "Your birthday is on "
         << date
         << "."
         << month
         << "."
         << year
         << "."
         << endl;
    
    system("PAUSE");
    return 0;
}   
    
    
int validnum(int lower,int higher)              //function to check whether number is valid
{
    int num = 0;    
    cin >> num;
    while((num < lower)||(num > higher))                    //tell user that number is invalid
    {
        cout << "Your number is invalid, please try again: ";
        cin >> num;
    }
    return num;
}

but it resulted in the following errors:
1. too many filenames. Type cc1plus -- help usage info.
2.unrecognized option 'quieu'
3.output filename specified twice

I thought this kind of errors might be a compiler problem, so I cheated and look at the book's answer key and inserted the code in the compiler:

Code:

#include <iostream> 
using namespace std;

int validNum(int lower, int upper);

int main()
{
  cout << "Enter your birthdate here.  Enter the year first. " << endl;
  int year = validNum(1900, 1998);

  cout << "Now the month. ";
  int month = validNum(1, 12);
  
  cout << "Now the date. ";
  int date = 0;
  switch(month)
  {
    case 1:
    case 3:
    case 5:
    case 7:
    case 8:
    case 10:
    case 12: 
      date = validNum(1, 31);
      break;
    case 4:
    case 6:
    case 9: 
    case 11:  
      date = validNum(1, 30);
      break;
    case 2: 
      if(0==year%4)
        date = validNum(1, 29);
      else
        date = validNum(1, 28);
  }

  cout << endl
       << "We have established that your date of birth is " 
       << month << "/" << date << "/" << year << "." << endl;

  return 0;
}

int validNum(int lower, int upper)
{
  int data = 0;   
  cout << "Please enter an integer between " << lower << " and " << upper << ": ";
  cin >> data;
  while(data < lower || data > upper) 
  {
    cout << "Invalid entry; please re-enter: ";
    cin >> data;
  }  
  return data;
}

As I have thought, the compiler returned the same errors. Is there anyway to fix this problem? Or must I change my compiler?

Nothing to do with your code, it's somewhere in the setup of your compiler / IDE

Like these
2.unrecognized option 'quieu'
3.output filename specified twice

I'd suggest you create a new project, and then copy/paste your code into the empty .cpp file it creates for you.