用C语言实现从文本文件中读取数据后进行排序的功能

#include <stdio.h>#include <stdlib.h>#include <conio.h>/*=============================  制作于：Aug 16, 2016  by QQ:1729403632===============================*/#define ST 64 //字符串大小void mergesort(int *, int);void _mergesort(int *, int, int, int *);void merge(int *, int, int, int, int *);char * s_gets(char *, int);int main(int argc, char * argv[]){  FILE * sor, * dest; //sor源文件 dest目标文件  int * ptr;//临时数组  int i, n; //n表示元素个数  char fname[ST]; //临时存储字符串  printf("请输入元素个数:");  while( scanf("%d", &n) != 1 || n <= 0 ){    printf("输入错误,请重新输入！/n");    while(getchar() != '/n')      continue;  }  while(getchar() != '/n')      continue;  ptr = (int *)malloc( (size_t)n * sizeof(int) ); //申请动态数组//////  if(ptr == NULL){    fprintf(stderr, "FAIL TO ASK FOR MEMORY SPACE/n");    exit(EXIT_FAILURE);  }  printf("请输入原文件名:");  if( s_gets(fname, ST) == NULL ){    fprintf(stderr, "Fail to get a string/n");    exit(EXIT_FAILURE);  }  sor = fopen(fname, "r"); //打开包含数据的源文件  if(sor == NULL){    fprintf(stderr, "Fail to open the source file/n");    exit(EXIT_FAILURE);  }  for(i = 0; i < n; i++) //获取数据到动态数组    if( fscanf(sor, "%d", &ptr[i]) != 1 ){      fprintf(stderr, "Fail to get the data/n");      exit(EXIT_FAILURE);    }  mergesort(ptr, n); //排序  printf("请输入要保存数据的文件名：");  if( s_gets(fname, ST) == NULL ){    fprintf(stderr, "Fail to get a string/n");    exit(EXIT_FAILURE);  }  dest = fopen(fname, "w"); //打开目标文件  if(dest == NULL){    fprintf(stderr, "Fail to open the destination file/n");    exit(EXIT_FAILURE);  }  for(i = 0; i < n; i++){ //输出数据到目标文件    if( fprintf(dest, "%d/t", ptr[i]) < 0 ){      fprintf(stderr, "Fail to save the data/n");      exit(EXIT_FAILURE);    }    if( ((i + 1) % 10) == 0){ //如果写满10个就换行      if( fprintf(dest, "/n") < 0 ){        fprintf(stderr, "Fail to save the data/n");        exit(EXIT_FAILURE);      }    }  }  if( fclose(sor) != 0 ){ //关闭源文件    fprintf(stderr, "Fail to close the source file/n");    exit(EXIT_FAILURE);  }  if( fclose(dest) != 0 ){ //关闭目标文件    fprintf(stderr, "Fail to close the destination file/n");    exit(EXIT_FAILURE);  }  free(ptr); //释放内存  printf("成功完成！/n请按任意键继续^ ^/b/b");  getch();  return 0;}void mergesort(int * ar, int size){  if(size > 0){    int * temp;    temp = (int *)malloc( (size_t)size * sizeof(int) ); /////    if(temp == NULL){      fprintf(stderr, "Fail to ask for MEMORY SPACE/n");      exit(EXIT_FAILURE);    }    _mergesort(ar, 0, size - 1, temp); //归并排序    free(temp);  }}void _mergesort(int * ar, int start, int end, int * temp){  if(start < end){    int mid = (start + end) / 2;    _mergesort(ar, start, mid, temp);  //左子数组排序    _mergesort(ar, mid + 1, end, temp);  //右子数组排序    merge(ar, start, mid, end, temp);  //合并子数组  }}void merge(int * ar, int p, int q, int r, int * temp){  int i = p, j = q + 1, k = 0;  while(i <= q && j <= r){    if(ar[i] < ar[j])      temp[k++] = ar[i++];    else      temp[k++] = ar[j++];  }  while(i <= q)  //如果序列[i...q]存在，追加    temp[k++] = ar[i++];  while(j <= r)  //如果序列[j...r]存在，追加    temp[k++] = ar[j++];  for(k = 0; k <= (r - p); k++)    ar[p + k] = temp[k];}char * s_gets(char * st, int size){  char * re;  int i = 0;  re = fgets(st, size, stdin);  if(re){    while(st[i] != '/n' && st[i] != '/0') //如果没有到输入字符串结束      i++;  //递增    if(st[i] == '/n') //如果字符串最后一个字符是'/n'      st[i] = '/0'; //把它变成'/0'    else //否则缓冲区内还有一部分超出读取范围的字符没有被读取      while(getchar() != '/n') //把这些字符读取完（清空缓冲区）        continue;  }  return re;}