下面是整个Ｃ/Ｃ++程序，但是它的结果是在运行界面直接输出的，你能给出几种方法让结果输出到一个文本里(即输出到一个以.txt后缀的文本中)．如果你能做到，将你的语句(实现这个输出的语句)直接给在这个程序中、或是给出你的修改．请积极发言，共同探讨！
程序是：
#include<iostream.h>
#include<stdio.h>
#include<string.h>
#include<ctype.h>
#include"search.h"
extern int reserve(char*);
extern void output(int,char*);
char token[20];
char ch;
int i,c;

void scanner(FILE *fp)
{
ch=fgetc(fp);
if(isalpha(ch))
{
token[0]=ch;
i=1;
ch=fgetc(fp);
while(isalpha(ch)||isalnum(ch))
{
token[i]=ch;
i++;
ch=fgetc(fp);
}
fseek(fp,-1,1);
token[i]='\0';
c=reserve(token);
if(c!=-1)
output(c,token);
else
output(10,token);
}
else if(isdigit(ch))
{
token[0]=ch;
ch=fgetc(fp);
i=1;
while(isdigit(ch))
{
token[i]=ch;
i++;
ch=fgetc(fp);
}
token[i]='\0';
fseek(fp,-1,1);
output(11,token);
}
else
switch(ch)
{
case'=':ch=fgetc(fp);
if(ch=='=')
output(39,"==");
else
{
fseek(fp,-1,1);
output(21,"=");
}
break;
case'+':output(22,"+");break;
case'-':output(23,"-");break;
case'*':output(24,"*");break;
case'/':output(25,"/");break;
case'(':output(26,"(");break;
case')':output(27,")");break;
case'[':output(28,"[");break;
case']':output(29,"]");break;
case'{':output(30,"{");break;
case'}':output(31,"}");break;
case',':output(32,",");break;
case':':output(33,":");break;
case';':output(34,";");break;
case'>':ch=fgetc(fp);
if(ch=='=')
output(37,">=");
else
{
fseek(fp,-1,1);
output(35,">");
}
break;
case'<':ch=fgetc(fp);
if(ch=='=')
output(38,"<=");
else
{
fseek(fp,-1,1);
output(36,"<");
}
break;
case'!':ch=fgetc(fp);
if(ch=='=')
output(40,"!=");
else
{
fseek(fp,-1,1);
output(-1,"ERROR!");
}
break;
}

}
void main()
{ FILE *fp;
char wenjian[30];
printf("Please input the file you want to transform:\n");
scanf("%s",&wenjian);
fp=fopen(wenjian,"r");
while(!feof(fp))
{
scanner(fp);
}
}

程序中的相关实现已包含在头文件"search.h"中，这点请不于疑虑！！