我还是个新手，还在学习C语言。目前，我的代码有问题。任务是删除文件IO中的某些内容，默认情况下，我的txt文件中有一些记录。该任务要求用户在txt文件中输入他/她想要删除的行。然而，问题出现了：
1(c程序在第一次仍能工作，但第二次、第三次及以下的程序无法工作。(这意味着可以在第一时间删除行(
我认为这是一个缓冲区问题，所以我添加了许多fflush代码，但仍然无法解决。
2( 我想将我的程序更改为使用关键字来查找记录并删除。用户键入记录号可以删除整个项目记录。然而，我不知道它是如何工作的。
如果有人能帮助我，我非常感激和高兴。1( 代码如下：
#include<stdio.h> #include<stdlib.h>
int main(){
FILE *fileptr1, *fileptr2, *fileptr3;
char filename[40]="itemrecord.txt";
char save;
int delete_line, temp = 1;
char reply;
printf("Enter file name: ");
scanf("%s", filename);
do{
//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);
}
//rewind
rewind(fileptr1);
fflush(stdout);
printf(" nn Enter line number of the line to be deleted <type 0 = not
delete anything>:");
fflush(stdin);
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("copy.c", "w");
save = 'a';
while (save != EOF)
{
save = getc(fileptr1);
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(save, fileptr2);
}
if (save == 'n')
{
temp++;
}
}
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);
}
fflush(stdout);
fflush(stdin);
fclose(fileptr1);
printf("nn Delete anther item?<y/n>: ");
scanf("%c",&reply);
}while(reply=='y' || reply=='Y');
return 0;
}
结果：
Enter file name:itemrecord
mary 1 123
sam 2 124
bob 3 125
Enter line number of the line to be deleted<type 0=not delete anything>:1
The contents of file after being changed are as follows:
sam 2 124
bob 3 125
Delete other record?<y/n>:y
sam 2 124
bob 3 125
Enter line number of the line to be deleted<type 0=not delete anything>:1
The contents of file after being changed are as follows:
sam 2 124
bob 3 125
Delete other record?<y/n>:n
//second time doesn't work.//
很抱歉代码太长，问题太长，但我太困惑了。。。
2( 如果我的记录进入
Mary
1
123
sam
2
124
bob
3
125
那么我怎样才能键入"玛丽"删除整个记录项目呢？类似的。。。
sam
2
124
bob
3
125
试试这个
int delete_line, temp;
char reply;
printf("Enter file name: ");
scanf("%s", filename);
do{
temp = 1;
....
我希望这能有所帮助。