One of the best ways to learn C programming is through practical exercises. This article will take you step-by-step through a project I recently completed: creating a simple phone book application. This program allows you to add, view, and delete contacts and demonstrates file handling and basic data management in C.
Detailed code explanation
Here is the complete code for the phone book application:
#include <stdio.h> #include <string.h> // 函数声明 void addContact(char name[], char number[]); void viewContacts(); void deleteContact(char name[]); int main() { int choice; char name[20]; char number[20]; printf("-- 欢迎使用您的电话簿! -- \n"); do { // 显示菜单 printf("\n您想执行什么操作?\n"); printf("1. 创建新联系人\t 2. 查看电话簿\t 3. 删除联系人\t 4. 退出\n"); scanf("%d", &choice); switch (choice) { case 1: // 添加新联系人 printf("很好,让我们创建一个新的联系人:\n"); printf("输入联系人的姓名:\n"); scanf("%s", name); printf("现在输入电话号码:\n"); scanf("%s", number); addContact(name, number); break; case 2: // 查看电话簿 printf("这是您的电话簿:\n"); viewContacts(); break; case 3: // 删除联系人 printf("输入要删除的联系人的姓名:\n"); scanf("%s", name); deleteContact(name); break; } } while (choice != 4); // 循环直到用户选择“退出” return 0; } // 向电话簿添加联系人的函数 void addContact(char name[], char number[]) { FILE *pFile; pFile = fopen("Phonebook.txt", "a"); if (pFile == NULL) { printf("打开电话簿时出错。"); return; } fprintf(pFile, "姓名: %s \t 电话: %s\n", name, number); printf("联系人已创建!\n"); fclose(pFile); } // 查看电话簿中所有联系人的函数 void viewContacts() { char fileContent[200]; FILE *pFile; pFile = fopen("Phonebook.txt", "r"); while (fgets(fileContent, sizeof(fileContent), pFile)) { printf("\n%s", fileContent); } fclose(pFile); } // 从电话簿中删除联系人的函数 void deleteContact(char name[]) { FILE *pFile, *pTrash; char line[200], contactName[20], contactNumber[20]; pFile = fopen("Phonebook.txt", "r"); pTrash = fopen("Trash.txt", "w"); if (pFile == NULL || pTrash == NULL) { printf("打开文件时出错。"); return; } while (fgets(line, sizeof(line), pFile)) { sscanf(line, "姓名: %s \t 电话: %s\n", contactName, contactNumber); if (strcmp(name, contactName) != 0) { fputs(line, pTrash); } } fclose(pFile); fclose(pTrash); // 将旧的电话簿替换为更新后的版本 remove("Phonebook.txt"); rename("Trash.txt", "Phonebook.txt"); printf("联系人已删除。"); }
Program functions
This program implements three key functions:
-
Add contact:
- Allow users to enter name and phone number.
- Store contacts in a file called Phonebook.txt.
-
View contact:
- Read and display all contacts stored in Phonebook.txt.
-
Delete contact:
- Delete contacts based on the name entered by the user.
- Create a temporary file to filter out deleted contacts and then replace the original file.
Key knowledge gained from this exercise
-
File processing in C language:
- Use fopen, fclose and file operation functions.
- Handle errors when a file cannot be opened or accessed.
-
String processing:
- Use functions such as strcmp and sscanf for string comparison and parsing.
-
Basic data management:
- Store and organize data in simple text files.
- Replace or update file contents by creating temporary files.
How to test code
- Copy the code into a .c file and compile it with a C compiler (e.g. gcc):
gcc -o phonebook phonebook.c
- Run the compiled program:
./phonebook
- Follow the on-screen instructions to add, view, or delete contacts.
- Open Phonebook.txt to verify that the data is stored as expected.
Potential improvements
This program is a great starting point, but here are some improvements you can try:
-
Input verification:
- Make sure the phone number is valid (i.e. only numeric characters).
- Prevent duplicate names from appearing in the phone book.
-
Improved UI:
- Provide more detailed instructions.
- Using fgets instead of scanf allows the use of multi-word names.
-
Enhanced file handling:
- Encrypt data for security.
- Use a structured format (such as CSV or JSON).
-
Advanced features:
- Implement search function to quickly find contacts.
- Sort phone book alphabetically.
Summary
This exercise helped me strengthen my understanding of file processing and basic data management in C language. It's a simple yet practical program that can serve as a building block for more complex projects. If you're new to C, give it a try - it's a fun and rewarding way to practice programming!
The above is the detailed content of Practicing C: Building a Simple Phonebook Application. For more information, please follow other related articles on the PHP Chinese website!

Mastering polymorphisms in C can significantly improve code flexibility and maintainability. 1) Polymorphism allows different types of objects to be treated as objects of the same base type. 2) Implement runtime polymorphism through inheritance and virtual functions. 3) Polymorphism supports code extension without modifying existing classes. 4) Using CRTP to implement compile-time polymorphism can improve performance. 5) Smart pointers help resource management. 6) The base class should have a virtual destructor. 7) Performance optimization requires code analysis first.

C destructorsprovideprecisecontroloverresourcemanagement,whilegarbagecollectorsautomatememorymanagementbutintroduceunpredictability.C destructors:1)Allowcustomcleanupactionswhenobjectsaredestroyed,2)Releaseresourcesimmediatelywhenobjectsgooutofscop

Integrating XML in a C project can be achieved through the following steps: 1) parse and generate XML files using pugixml or TinyXML library, 2) select DOM or SAX methods for parsing, 3) handle nested nodes and multi-level properties, 4) optimize performance using debugging techniques and best practices.

XML is used in C because it provides a convenient way to structure data, especially in configuration files, data storage and network communications. 1) Select the appropriate library, such as TinyXML, pugixml, RapidXML, and decide according to project needs. 2) Understand two ways of XML parsing and generation: DOM is suitable for frequent access and modification, and SAX is suitable for large files or streaming data. 3) When optimizing performance, TinyXML is suitable for small files, pugixml performs well in memory and speed, and RapidXML is excellent in processing large files.

The main differences between C# and C are memory management, polymorphism implementation and performance optimization. 1) C# uses a garbage collector to automatically manage memory, while C needs to be managed manually. 2) C# realizes polymorphism through interfaces and virtual methods, and C uses virtual functions and pure virtual functions. 3) The performance optimization of C# depends on structure and parallel programming, while C is implemented through inline functions and multithreading.

The DOM and SAX methods can be used to parse XML data in C. 1) DOM parsing loads XML into memory, suitable for small files, but may take up a lot of memory. 2) SAX parsing is event-driven and is suitable for large files, but cannot be accessed randomly. Choosing the right method and optimizing the code can improve efficiency.

C is widely used in the fields of game development, embedded systems, financial transactions and scientific computing, due to its high performance and flexibility. 1) In game development, C is used for efficient graphics rendering and real-time computing. 2) In embedded systems, C's memory management and hardware control capabilities make it the first choice. 3) In the field of financial transactions, C's high performance meets the needs of real-time computing. 4) In scientific computing, C's efficient algorithm implementation and data processing capabilities are fully reflected.

C is not dead, but has flourished in many key areas: 1) game development, 2) system programming, 3) high-performance computing, 4) browsers and network applications, C is still the mainstream choice, showing its strong vitality and application scenarios.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Zend Studio 13.0.1
Powerful PHP integrated development environment

Atom editor mac version download
The most popular open source editor

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 Mac version
God-level code editing software (SublimeText3)
