如何在C中搜索和更新文件中的数据? [英] How to search and update data in files in C?
问题描述
我正在做一个关于C语言超市中使用的客户详细信息的项目。
首先,我将输入所有客户详细信息,例如客户ID,姓名,电话号码,信用积分,...... ..到文件。
然后如何使用文件中的客户ID或电话号码搜索特定客户。
如何更新他的信用积分。每购买100美元,客户将获得1个积分。
我尝试过:
读取文件末尾的文件。
I am doing a project on customer details used in a supermarket in C language.
First I will enter all the customer details such as customer Id,name,phone number, credit points,....into a file.
Then how to search for a particular customer using customer id or phone number in the file.
How to update his credit points. 1 credit point will be given to a customer for every purchase of $100.
What I have tried:
reading a file upto end of the file.
推荐答案
100。
我尝试了什么:
读取文件末尾的文件。
100.
What I have tried:
reading a file upto end of the file.
一般来说你需要:
- 将文件读入内存
- 修改内存内容
- 回写修改后的内存内容到原始文件(覆盖它)
Generally speaking you need to:
- read the file into memory
- modify the memory content
- write back the modified memory content to the original file (overwriting it)
或多或少,你在一个文件中创建一个数据库。
如果你不关心细节,每个操作涉及完整的文件重写te。
More or less, you are creating a database in a file.
If you don't take care about details, every operation involve a complete file rewrite.
然后如何使用文件中的客户ID或电话号码搜索特定客户。
Then how to search for a particular customer using customer id or phone number in the file.
重新读取文件,找到每条记录所需的字段并寻找匹配。
1避免解决方案重写问题是使用固定长度字段,就像dBase一样。 .dbf - 维基百科,免费的百科全书 [ ^ ]
或求助于SQL
by rereading the file, locating the needed field of each record and looking for a match.
1 solution to avoid the rewriting problem is to use fixed length fields just like dBase used to do. .dbf - Wikipedia, the free encyclopedia[^]
or resort to SQL
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