#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
{
    int n_len,i,j;
    char temp[100],outname[4][6]={"1.txt","2.txt","3.txt","4.txt"};
    FILE * in,*out[4];
    if((in=fopen("123.txt","r"))==NULL)
    {
        printf("cant open the file 123.txt\n\n");
        exit(0);
    }
    else
        printf("open the file 123.txt successful!\n\n");

    for(i=0;i<4;i++)
        if((in=fopen(outname[i],"w+"))==NULL)
        {
            printf("cant open the file %s\n\n",outname[i]);
            exit(0);
        }
        else
            printf("open the file %s successful!\n\n",outname[i]);

    n_len=fread(temp,1,100,in);
    printf("%d\n",n_len);
    for(i=0,j=0;i<n_len;i++)
    {
        fwrite(&temp[i],1,1,out[j]);

        if(i%4==3)
            j++;
    }

    fcloseall();
        
    return 0;

}


结果n_len=0，生成的4个txt都是空的。   123.txt内容是1111222233334444

你们贴代码的时候为什么不加上代码标签

为什么在打开123.text文件后不马上读取

读和写的文件指正怎么能共用一个in

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
{
    int n_len,i,j;
    char temp[100],outname[4][6]={"1.txt","2.txt","3.txt","4.txt"};
    FILE * in,*out[4];
    if((in=fopen("123.txt","r"))==NULL)
    {
        printf("can't open the file 123.txt\n\n");
        exit(0);
    }
    else
        printf("open the file 123.txt successful!\n\n");

    n_len=fread(temp,1,100,in);
    printf("%d\n",n_len);
    for(i=0;i<4;i++)
        if((in=fopen(outname[i],"w+"))==NULL)
        {
            printf("cant open the file %s\n\n",outname[i]);
            exit(0);
        }
        else
            printf("open the file %s successful!\n\n",outname[i]);
    for(i=0,j=0;i<n_len;i++)
    {
        fwrite(&temp[i],1,1,out[j]);

        if(i%4==3)
            j++;
    }

    fcloseall();
        
    return 0;

}

能出结果了虽然结果没错，但是有问题你用了一个指针打开五个文件，应该每次打开后关闭它

我知道哪错了，后面四个用in的指针应该是out[i]的。

谢谢。问一下代码标签就是指的注释吗

文本编辑框顺数第6个图标