int& intswap(int& a, int& b)

{

    b ^= a;

    a ^= b;

    b ^= a;

    return b;

}

string & strswap(string & a, string & b)

{

    a=a.append(b);

    b= a.substr(,a.length()-b.length());

    a=a.substr(b.length(),a.length());

    return b;

}

//不使用动态内存：

char* cswap(char* a, char* b)

{

    int i = ;

    int alen = strlen(a),blen= strlen(b);

    strcat(a, b);

    for (;i < alen;i++)

    {

        b[i] = a[i];

    }

    b[i] = '\0';

    for (i = ;i < blen;i++)

    {

        a[i] = a[alen + i];

    }

    a[i] = '\0';

    return a;

}

// 使用动态内存

int charswap(char *a, char *b)

{

    char* temp=NULL;
    int n = strlen(a) > strlen(b) ? (strlen(a)+1) : (strlen(b)+1);

    temp = (char*)malloc(n * sizeof(char));

    strcpy(temp, a);

    strcpy(a, b);

    strcpy(b, temp);

    free(temp);

    return ;

}

 #include<iostream>

 #include<string.h>

 using namespace std;

 int main(void)

 {

     clock_t start, finish;

     char a[] ="hellohellohellohellohellohellohellohellohellohello";

     char b[] = "hihihihihihihihihihihi";

     int alen = strlen(a);

     int blen = strlen(b);

     start = clock();

     for (int i = ;i < ;++i)

     {

         cswap(a, b);

         //charswap(a, b);

     }

     finish = clock();

     double t = (finish - start)/CLOCKS_PER_SEC ;

     cout << "costs: " << t << "s" << endl;

     cout << "a= " << a << endl;

     cout << "b= " << b << endl;

     return ;

 }