C++ Tutorial/Function/function overload

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Create overloaded print() and println() functions that display various types of data

#include <iostream> 
using namespace std; 
 
void println(bool b); 
void println(int i); 
void println(long i); 
void println(char ch); 
void println(char *str); 
void println(double d); 
 
void print(bool b); 
void print(int i); 
void print(long i); 
void print(char ch); 
void print(char *str); 
void print(double d); 
 
int main() 
{ 
  println(true); 
  println(1); 
  println("test"); 
  println("x"); 
  println(9L); 
  println(1.23); 
 
  print("string"); 
  print(false); 
  print(" "); 
  print(8); 
  print(" "); 
  print(100L); 
  print(" "); 
  print(1.01); 
 
  println(" Done!"); 
 
  return 0; 
} 
 
void println(bool b) 
{ 
  if(b) 
    cout << "true\n"; 
  else 
    cout << "false\n"; 
} 
 
void println(int i) 
{ 
  cout << i << "\n"; 
} 
 
void println(long i) 
{ 
  cout << i << "\n"; 
} 
 
void println(char ch) 
{ 
  cout << ch << "\n"; 
} 
 
void println(char *str) 
{ 
  cout << str << "\n"; 
} 
 
void println(double d) 
{ 
  cout << d << "\n"; 
} 
 
void print(bool b) 
{ 
  if(b) 
     cout << "true"; 
  else 
     cout << "false"; 
} 
 
void print(int i) 
{ 
  cout << i; 
} 
 
void print(long i) 
{ 
  cout << i; 
} 
 
void print(char ch) 
{ 
  cout << ch; 
} 
 
void print(char *str) 
{ 
  cout << str; 
} 
 
void print(double d) 
{ 
  cout << d; 
}
true
1
test
x
9
1.23
stringfalse 8 100 1.01 Done!

Default Arguments vs. Overloading

#include <iostream>
#include <cstring>
using namespace std;
   
void mystrcat(char *s1, char *s2, int len = -1);
   
int main()
{
  char str1[80] = "This is a test";
  char str2[80] = "0123456789";
   
  mystrcat(str1, str2, 5); // concatenate 5 chars
  cout << str1 << "\n";
   
  strcpy(str1, "This is a test"); // reset str1
   
  mystrcat(str1, str2); // concatenate entire string
  cout << str1 << "\n";
   
  return 0;
}
   
// A custom version of strcat().
void mystrcat(char *s1, char *s2, int len)
{
  // find end of s1
  while(*s1) s1++;
   
  if(len == -1) len = strlen(s2);
   
  while(*s2 && len) {
    *s1 = *s2; // copy chars
    s1++; 
    s2++;
    len--;
  }
 
  *s1 = "\0"; // null terminate s1
}

Finding the Address of an Overloaded Function

#include <iostream>
using namespace std;
   
int myfunc(int a);
int myfunc(int a, int b);
   
int main()
{
  int (*fp)(int a); // pointer to int f(int)
   
  fp = myfunc; // points to myfunc(int)
   
  cout << fp(5);
   
  return 0;
}
   
int myfunc(int a)
{
  return a;
}
   
int myfunc(int a, int b)
{
  return a*b;
}

Overload a function three times.

#include <iostream> 
using namespace std; 
 
void f(int i);        
void f(int i, int j); 
void f(double k);     
 
int main() 
{ 
  f(10);     // call f(int) 
 
  f(10, 20); // call f(int, int) 
 
  f(12.23);  // call f(double) 
 
  return 0; 
} 
 
void f(int i) 
{ 
  cout << "In f(int), i is " << i << "\n"; 
} 
 
void f(int i, int j) 
{ 
  cout << "In f(int, int), i is " << i; 
  cout << ", j is " << j << "\n"; 
} 
 
void f(double k) 
{ 
  cout << "In f(double), k is " << k << "\n"; 
}
In f(int), i is 10
In f(int, int), i is 10, j is 20
In f(double), k is 12.23

Overload function by parameter type: int, double and long

#include <iostream>  
using namespace std;  
 
int neg(int n);       // neg() for int. 
double neg(double n); // neg() for double. 
long neg(long n);     // neg() for long. 
 
 
int main()  
{  
 
  cout << "neg(-10): " << neg(-10) << "\n"; 
  cout << "neg(9L): " << neg(9L) << "\n"; 
  cout << "neg(11.23): " << neg(11.23) << "\n"; 
  
  return 0;  
} 
 
// neg()for int. 
int neg(int n) 
{ 
  return -n; 
} 
 
// neg()for double. 
double neg(double n) 
{ 
  return -n; 
} 
 
// neg()for long. 
long neg(long n) 
{ 
  return -n; 
}
neg(-10): 10
neg(9L): -9
neg(11.23): -11.23

Overload functions with two parameters

#include <iostream>  
using namespace std;  
 
int min(int a, int b);     // min() for ints 
char min(char a, char b);  // min() for chars 
int * min(int *a, int *b); // min() for int pointers 
 
int main()  
{  
  int i=10, j=22; 
 
  cout << "min("X", "a"): " << min("X", "a") << "\n"; 
  cout << "min(9, 3): " << min(9, 3) << "\n"; 
  cout << "*min(&i, &j): " << *min(&i, &i) << "\n"; 
  
  return 0;  
} 
 
// min() for ints.  Return the smallest value. 
int min(int a, int b) 
{ 
  if(a < b) return a; 
  else return b; 
} 
 
// min() for chars -- ignore case. 
char min(char a, char b) 
{ 
  if(tolower(a) < tolower(b)) return a; 
  else return b; 
} 
 
/* 
   min() for int pointers.  
   Compare values and return pointer to smallest value. 
*/ 
int * min(int *a, int *b) 
{ 
  if(*a < *b) return a; 
  else return b; 
}
min("X", "a"): a
min(9, 3): 3
*min(&i, &j): 10

Overload function with array type

#include<iostream.h>
#include<iomanip.h>
int findmax(int intArray[]);
float findmax(float floatArray[]);
double findmax(double doubleArray[]);
int findmin(int intArray[]);
float findmin(float floatArray[]);
double findmin(double doubleArray[]);
main()
{
  int intArray[10]={1,8,4,2,3,0,9,3,5,7};
  float floatArray[10]={145.15,312.3,3163.2,119.13,710.1,315.4,511.2,513.7,319.4,519.2};
  double doubleArray[10]={15.12354323,2.41237763,63.29123876,19.67123863,
   78.34123541,35.44123009,51.21230392,53.40123967,39.80612304,59.11111232};
  cout<<"largest value in the intArray is "<<(findmax(intArray))<<"\n";
  cout<<"largest value in the floatArray is "<<(findmax(floatArray))<<"\n";
  cout<<"largest value in the doubleArray is "<<(findmax(doubleArray))<<"\n";
  cout<<"smallest value in the intArray is "<<(findmin(intArray))<<"\n";
  cout<<"smallest value in the floatArray is "<<(findmin(floatArray))<<"\n";
  cout<<"smallest value in the doubleArray is "<<(findmin(doubleArray))<<"\n";
  return 0;
}
int findmax(int intArray[])
{
   int max=0;
   for(int i=0;i<10;i++)
   {
     if(intArray[i]>max)
        {
          max=intArray[i];
        }
   }
   return max;
}
float findmax(float floatArray[])
{
   float max=0;
   for(int i=0;i<10;i++)
   {
     if(floatArray[i]>max)
        {
          max=floatArray[i];
        }
   }
   return max;
}
double findmax(double doubleArray[])
{
   double max=0;
   for(int i=0;i<10;i++)
   {
     if(doubleArray[i]>max)
        {
          max=doubleArray[i];
        }
   }
   return max;
}
int findmin(int intArray[])
{
   int min=999;
   for(int i=0;i<10;i++)
   {
     if(intArray[i]<min)
        {
          min=intArray[i];
        }
   }
   return min;
}
float findmin(float floatArray[])
{
   float min=9999.9;
   for(int i=0;i<10;i++)
   {
     if(floatArray[i]<min)
        {
          min=floatArray[i];
        }
   }
   return min;
}
double findmin(double doubleArray[])
{
   double min=9999.9;
   for(int i=0;i<10;i++)
   {
     if(doubleArray[i]<min)
        {
          min=doubleArray[i];
        }
   }
   return min;
}
largest value in the intArray is 9
largest value in the floatArray is 3163.2
largest value in the doubleArray is 78.3412
smallest value in the intArray is 0
smallest value in the floatArray is 119.13
smallest value in the doubleArray is 2.41238

Overloading a function with const reference parameters

#include <iostream>
using std::cout;
using std::endl;
double larger(double a, double b);
long larger(const long& a, const long& b);
int main() {
  double a_double = 1.5, b_double = 2.5;
  cout << larger(a_double, b_double) << endl;
 
  int a_int = 15, b_int = 25;
  cout << larger(static_cast<long>(a_int), static_cast<long>(b_int))<< endl;
  return 0;
}
double larger(double a, double b) {
  cout << "double larger() called" << endl;
  return a>b ? a : b;
}
long larger(const long& a, const long& b) {
  cout << "long ref larger() called" << endl;
  return a>b ? a : b;
}
double larger() called
2.5
long ref larger() called
25

Overloading a function with reference parameters

#include <iostream>
#include <iomanip>
using namespace std;
double larger(double a, double b);
long& larger(long& a, long& b);

int main()
{
  cout << larger(1.5, 2.5) << endl;
 
  cout << larger(static_cast<long>(12), static_cast<long>(13))
       << endl;
  return 0;
}
double larger(double a, double b)
{
  cout << " double version. ";
  return a>b ? a : b;
}
long& larger(long& a, long& b)
{
  cout << " long ref version. ";
  return a>b ? a : b;
}
double version. 2.5
 double version. 13

Overloading functions with difference in number of parameters

#include <iostream>
using namespace std;
int myfunc(int i); // 
int myfunc(int i, int j);
int main()
{
  cout << myfunc(10) << " "; // calls myfunc(int i)
  cout << myfunc(4, 5); // calls myfunc(int i, int j)
  return 0;
}
int myfunc(int i)
{
  return i;
}
int myfunc(int i, int j)
{
  return i*j;
}
10 20"