写点C++ 学习记录 充数

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#include "stdafx.h"
#include <cstdlib>
#include <iostream>
 
using namespace std;
 
int fcmp(const void* elem,const void* elem2);
void sample1();
void sample2();
 
int _tmain(int argc, _TCHAR* argv[])
{
    sample1();
    cout << "*******************" << endl;
    sample2();
 
    return 0;
}
 
 
template <class T>
struct plus{
    T operator()(const T& x,const T& y)const{return x+y;}
};
 
template <class T>
struct minus{
    T operator()(const T& x,const T& y)const{return x-y;}
};
 
void sample2()
{
    plus<int>plusobj;
    minus<int>minusobj;
 
    cout << plusobj(3,5) << endl;
    cout << minusobj(3,5) << endl;
 
    cout << plus<int>()(43,50) << endl;
    cout << minus<int>()(43,50) << endl;
 
}
 
 
void sample1()
{
    int ia[10] = {32,92,67,58,10,4,25,52,59,54};
    for(int i =0;i <10;i++)
    {
        cout << ia[i] << " ";
    }
    cout << endl;
 
    qsort(ia,sizeof(ia)/sizeof(int),sizeof(int),fcmp);
 
    for(int i =0;i <10;i++)
    {
        cout << ia[i] << " ";
    }
    cout << endl;
}
 
int fcmp(const void* elem1,const void* elem2)
{
    const int* i1 = (const int*)elem1;
    const int* i2 = (const int*)elem2;
 
    if(*i1 < *i2)
        return -1;
    else if(*i1 == *i2)
        return 0;
    else if(*i1 > *i2)
        return 1;
}

传递函数指针与function call 示例

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