// l10_1.2.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<conio.h>
#include<stdlib.h>
#include<string.h>
#define SIZE 10
int _tmain(int argc, _TCHAR* argv[])
{
    FILE*fp;
    char ch1[SIZE];
    char ch2[SIZE];
    char ch3[SIZE];
    printf("请输入三个字符串：\n");
    gets(ch1);
    gets(ch2);
    gets(ch3);
    if((fp=fopen("string.txt","w"))==NULL)
    {
        printf("Cannot open file strike any key exit!");
        exit(-1);
    }
    fputs(ch1,fp);
    fputs(ch2,fp);
    fputs(ch3,fp);
    fclose(fp);
    char ch4[SIZE*3]={0};
    if((fp=fopen("string.txt","r"))!=NULL)
    {
        
        fgets(ch4,SIZE*3,fp);
        printf("您输入的字符串为：");
        puts(ch4);
        fclose(fp);
    }
    char ch5[SIZE*3];
    if((fp=fopen("string2.txt","w"))==NULL)
    {
        printf("Cannot open file strike any key exit!");
        exit(-1);
    }
    strcpy(ch5,ch4);
    fputs(ch5,fp);
    fclose(fp);
    if((fp=fopen("string2.txt","r"))==NULL)
    {
        printf("Cannot open file strike any key exit!");
        exit(-1);
    }
    fgets(ch5,SIZE*3,fp);
    fclose(fp);
    _getch();
    return 0;
}

红色的字体是复制已有的文件内容

什么问题啊？我可以运行诶

还是用二进制复制比较好，你那个只能复制，二进制的话可以复制任何文件的。

#include <stdio.h>

int main(int argc, char **argv)
{
    char buffer[1024];
    char *srcFile = "src";
    char *desFile = "des";

    FILE *srcfp = NULL;
    FILE *desfp = NULL;

    if (argc == 3)
    {
        srcfp = fopen(argv[1], "rb");
        desfp = fopen(argv[2], "wb");
    }
    else
    {
        srcfp = fopen(srcFile, "rb");
        desfp = fopen(desFile, "wb");
    }

    if ((srcfp == NULL) || (desfp == NULL))
        return -1;

    for (;;)
    {
        if (feof(srcfp))
            break;

        int readSize = fread(buffer, 1, 1024, srcfp);
        fwrite(buffer, 1, readSize, desfp);
    }

    fclose(srcfp);
    fclose(desfp);

    return 0;
}