Question

C语言中，读取一个TXT文件，然后对其内容进行更改，如何将更改的内容进行保存

#include <iostream>
using namespace std;
void main()
{
FILE * fp; char ch;
char chh;
char g[600];
int i=0;
if((fp=fopen("3.txt","r"))==NULL)
{
cout << "Error.";
exit(0);
}
while((ch=fgetc(fp))!=EOF)
{
g[i]=ch;
if(i%1==0&&i!=0)
cout<<",";
if(i%8==0)
cout<<endl;
cout << g[i];
i++;
}
fclose(fp);
system("pause");
}

Answer 1

把cout重定向到文件：
------------------------------------------------------
#include <iostream>
#include <fstream>
using namespace std;
int main()
{   
ofstream outfile("out.txt");
streambuf *streams=cout.rdbuf();//保存原来的cout对象
cout.rdbuf(outfile.rdbuf());
cout<<"yanghaijunlovechenchen!sssssssssssssssssssssssssssssssssssss"<<endl;
cout<<"yanghaijunlovechenchen!sssssssssssssssssssssssssssssssssssss"<<endl;
cout<<"yanghaijunlovechenchen!sssssssssssssssssssssssssssssssssssss"<<endl;
cout<<"yanghaijunlovechenchen!sssssssssssssssssssssssssssssssssssss"<<endl;
cout.rdbuf(streams);//恢复对象 保存和恢复必须成对出现不然会出现错误
cout<<"yanghaijunlovechenchen!"<<endl;
return 0;
}

Answer 2

#include <stdio.h>
int main(void)
{
    FILE *fp;
    FILE *fp2;
    char ch;
    char chh;
    char g[600];
    int i=0;
    if((fp=fopen("3.txt","r"))==NULL)
    {
        printf("Error.");
        return (0);
    }
    if((fp2=fopen("4.txt","w"))==NULL)
    {
        printf("Error 2.");
        return (0);
    }
    while((ch=fgetc(fp))!=EOF)
    {
        g[i]=ch;
        if(i%1==0&&i!=0)
        fputc(',', fp2);
        if(i%8==0)
        {
            fputc('\n', fp2);
        }
        fputc(g[i], fp2);;
        i++;
    }
    fclose(fp);
    fclose(fp2);
    printf("Done\n");
    getchar();
}