C++ Tutorial/Function/function overload — различия между версиями
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Текущая версия на 10:29, 25 мая 2010
Содержание
- 1 Create overloaded print() and println() functions that display various types of data
- 2 Default Arguments vs. Overloading
- 3 Finding the Address of an Overloaded Function
- 4 Overload a function three times.
- 5 Overload function by parameter type: int, double and long
- 6 Overload functions with two parameters
- 7 Overload function with array type
- 8 Overloading a function with const reference parameters
- 9 Overloading a function with reference parameters
- 10 Overloading functions with difference in number of parameters
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"
