我正在尝试编写一个程序来删除文件 io 中的记录。文件内容默认设置。现在我正在尝试将我的文本文件内容放入数组中,但是出现了一些问题....
首先是我默认的数据文件内容:
1001
eric
1
human
10
70.00
eric
home
arrive
1002
She
1
human
10
50.00
she
home
arrive
1003
She_eric
2
human
10
120.00
eric
home
arrive
这是我的代码:(我正在使用 fscanf 将我的文本文件数据放入数组中,您可以在打开文件以供读取的中间看到它)
#include <stdio.h>
#include <stdlib.h>
struct record{
char recordnum [40];
char itemrecord [40];
char quantity [40];
char weight [40];
char itemname [40];
char catagory [40];
char recipient [40];
char final_destination [40];
char status [40];
};
int main()
{
FILE *fileptr1, *fileptr2, fileptr3;
char filename[40]="record.txt";
char save;
int delete_num, temp ;
char reply;
#define MAX 9
struct record Arr[MAX];
printf("Enter file name: ");
scanf("%s", filename);
do{
temp =1; //reset temp and loop can work below time
//open file in read mode
fileptr1 = fopen(filename, "r");
if (fileptr1== NULL){
printf("open unsuccessful,file not exist");
exit(1);
}
save = getc(fileptr1);
while (save != EOF)
{
printf("%c", save);
save = getc(fileptr1);
int i =0;
for (i=0; i<3 ; i++){
fscanf(fileptr1,"%s %s %s %s %s %s %s %s %s", Arr[i].recordnum,
Arr[i].itemname, Arr[i].itemrecord, Arr[i].catagory, Arr[i].quantity,
Arr[i].weight, Arr[i].recipient, Arr[i].final_destination, Arr[i].status
);
}
}
//rewind
rewind(fileptr1);
printf(" \n\n Enter record number to be deleted <type 0 = not delete
anything>:");
fflush(stdin);
scanf("%d", &delete_num);
//open new file in write mode
fileptr2 = fopen("copy.c", "w");
save = getc(fileptr1);
while (save != EOF)
{
save = getc(fileptr1);
//except the line to be deleted
int i ;
for (i=0;i<3;i++){
if (temp != delete_num)
{
//copy all lines in file replica.c
putc(save, fileptr2);
}}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("copy.c", filename);
fflush(stdout);
printf("\nThe contents of file after being changed are as follows:\n");
fileptr1 = fopen(filename, "r");
save = getc(fileptr1);
while (save != EOF)
{
printf("%c", save);
save = getc(fileptr1);
}
fclose(fileptr1);
fflush(stdin);
printf("\n\n Delete anther item?<y/n>: ");
scanf("%c",&reply);
}while(reply=='y' || reply=='Y');
return 0;
}
对不起我的长代码......
结果:
Enter file name:record.txt
10
Enter record number to be deleted <type 0 = not delete anything>:1001
The contents of file after being changed are as follows:
0000000111
eeerrriiiccc
111
hhhuuummmaaannn
111000
777000...000
eeerrriiiccc
hhhooommmeee
aaarrrrrriiivvveee
和下面的结果相同......有趣......
这不是我预期的结果...我知道这个词出现了三次因为我的 for 循环。但是我希望我的 for 循环运行 3 次,第一次包括 9record 及以下..
您正在使用 getc
从文件中读取字符,然后丢弃它们。所以你很可能会丢失有意义的字符。您也没有检查 fscanf 的返回值以查看它是否成功,从而留下了在没有意识到的情况下出错的可能性。您可以通过摆脱 getc
调用并使用 fscanf
的返回值来控制循环来解决这两个问题:
while (fscanf(fileptr1,"%39s%39s%39s%39s%39s%39s%39s%39s%39s",
Arr[i].recordnum, Arr[i].itemname, Arr[i].itemrecord,
Arr[i].catagory, Arr[i].quantity, Arr[i].weight,
Arr[i].recipient, Arr[i].final_destination, Arr[i].status) == 9) {
if (++i >= MAX)
break;
}
然后,要写入文件,您要删除请求的记录,而不仅仅是一行。因此,最好的办法是使用您之前读入 Arr
的数据从头开始(重新)写入文件,并忽略要删除的记录。
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