C语言实现文件内容按行随机排列的算法示例

#!/bin/sh### note: sh random.sh in_fname out_fname ###infile=$1outfile=$2line_num=`cat $infile | wc -l `./random $line_num $infile $outfile.tmpsort $outfile.tmp -k 2 -n -t ' ' | cut -f1 > $outfile

//random.c#include <string>#include <iostream>#include <ctime>#include <cstdlib>using namespace std;const int LEN = 4098;//返回属于[p,q)的随机整数int rand(int p, int q){   int size = q-p+1;   return p+ rand()%size;}//交换两个元素值void swap(int& a , int& b){   int temp = a;   a = b;   b = temp;}//打印数组值void print(int *v, int n){    for(int i=0; i < n ; i++)    {        printf("%u/n", v[i]);    }}//给数组a[n], 随机不重复赋值[1,n]之间的数void randomize(int *v, int n){    //initialize    for(int i=0; i < n; i++)    {        v[i] = i+1;    }    for(int i=n-1; i>0; i--)    {        int r = rand(0,i+1);        swap(v[r], v[i]);    }}//删除换行符int chomp(char *str){  int len = strlen(str);  while(len > 0 && (str[len - 1] == '/n' || str[len - 1] == '/r'))  {    str[len - 1] = 0;    len--;  }  return len;}//主函数int main(int argc, char *argv[]){    int line_num = atoi(argv[1]);    printf("%u/n",line_num);    int *value = (int*)malloc((line_num) * sizeof(int));    printf("%u/n",line_num);    randomize(value, line_num);    //print(value, N);    FILE* infile = fopen(argv[2], "r");    if( infile == NULL )    {        printf("Cann't open file %s.", argv[1]);        return 0;    }    FILE* outfile = fopen(argv[3], "w");    if( outfile == NULL)    {        printf("Cann't open file %s to write.", argv[2]);        return 0;    }    int i=0;    char str[LEN];    str[0] = 0;    str[LEN-1] = 0;    while( !feof(infile) )    {        if( !fgets(str, sizeof(str),infile))        {            break;        }        str[LEN- 1] = 0;        chomp(str);        fprintf(outfile, "%s/t%u/n", str, value[i]);        i++;    }    fclose(infile);    fclose(outfile);    return 0;}