#include <iostream>#include <stdlib.h>using namespace std;int compared(const void *key1,const void *key2){//cout<<"enter compare"<<endl;const int* iKey1 = (int*)key1;const int* iKey2 = (int*)key2;//cout<<*iKey1<<endl;//cout<<*iKey2<<endl;if(*iKey1>*iKey2){//cout<<"big"<<endl;return 1;}else if(*iKey1==*iKey2){//cout<<"equal"<<endl;return 0;}else if(*iKey1<*iKey2){//cout<<"less"<<endl;return -1;}}//k设置为size-1//i设置为0//j设置为中间数static int merge(void* data, int esize, int i, int j, int k, int (*compare)(const void* key1,const void* key2)){ char *a = (char*)data, *m=NULL; int ipos, jpos, mpos; ipos = i; jpos = j+1; mpos = 0; if((m=(char*)malloc(esize*((k-i)+1)))==NULL ){return -1;} while(ipos<=j||jpos<=k){if(ipos>j){//the left elements has no more elements to mergewhile(jpos<=k){memcpy(&m[mpos*esize],&a[jpos*esize],esize);jpos++;mpos++;}continue;}else if(jpos>k){//right division has no more elements to merge.while(ipos<=j){memcpy(&m[mpos*esize],&a[ipos*esize],esize);ipos++;mpos++;}continue;}if(compare(&a[ipos*esize],&a[jpos*esize])<0){memcpy(&m[mpos*esize],&a[ipos*esize],esize);ipos++;mpos++;}else{memcpy(&m[mpos*esize],&a[jpos*esize],esize);jpos++;mpos++;}}//prepare to merge datamemcpy(&a[i*esize], m,esize*((k-1)+1));free(m);return 0; } int mgsort(void *data, int size, int esize, int i,int k,int (*compare)(const void* key1,const void* key2)){int j;//stop the recursion when no more element divisions can be made.if(i<k){//determine where to divide the elementsj = (int)(((i+k-1))/2);if(mgsort(data,size,esize,i,j,compared)<0){return -1;}if(mgsort(data,size,esize,j+1,k,compared)<0){return -1;}//merge the two sorted divisions into a single sorted setif(merge(data,esize,i,j,k,compared)<0){return -1;}}return 0;}int main(int argc, char *argv[]){int a[]={4,2,5,8,4,6};for(int i=0;i<6;i++){cout<<a[i]<<",";}cout<<endl;mgsort(a,6,4,0,5,compared);for(int i=0;i<6;i++){cout<<a[i]<<",";}cout<<endl; system("PAUSE"); return 0;}
