How to define the call declaration format of c language function
Apr 04, 2025 am 06:03 AM
C language functions include definitions, calls and declarations. Function definition specifies function name, parameters and return type, function body implements functions; function calls execute functions and provide parameters; function declaration tells the compiler the function type. Value pass is used for parameter pass, pay attention to the return type, maintain a consistent code style, and handle errors in functions. Mastering this knowledge can help write elegant, robust C code.
C language functions: things that define, call and declare
You must be thinking about what the definition, call and declaration of C language functions are, and how to write them to make the compiler obedient and the program not report errors? Don't worry, let's talk slowly. This article not only teaches you grammar, but also helps you understand the logic behind it and avoid those crazy pitfalls. After reading it, you can write elegant and efficient C functions instead of a bunch of headache-inducing code.
Let’s talk about the basics first. In C language, functions are the basic unit of organizing code, just like bricks that build blocks. You have to know how to define them and how to use them to build a beautiful "house".
Function definition is like giving shapes and functions to blocks. It contains function name, parameter list (input), return type (output), and function body (implementation).
<code class="c">// 函數(shù)定義：一個(gè)計(jì)算兩個(gè)數(shù)平方和的函數(shù)int square_sum(int a, int b) { // 函數(shù)體：計(jì)算平方和int sum = a * ab * b; return sum; // 返回計(jì)算結(jié)果}</code>
Here, int square_sum(int a, int b) is part of the function declaration, which tells the compiler: this function is called square_sum , which receives two integers a and b as input and returns an integer. The function body is enclosed in curly braces {} , which contains specific calculation logic.
Function calls are like using blocks of blocks you defined. You just need to provide the correct parameters and the function will execute and return the result.
<code class="c">#include <stdio.h> int main() { int x = 3, y = 4; int result = square_sum(x, y); // 調(diào)用square_sum函數(shù)printf("The square sum of %d and %d is: %d\n", x, y, result); // 打印結(jié)果return 0; }</stdio.h></code>
In the main function, square_sum(x, y) is a function call. The compiler will find the definition of the square_sum function, execute the code inside, and assign the result result . Note that the type of the parameter must match the parameter type in the function definition, otherwise the compiler will report an error.
Function declaration This is like putting a label on a building block and telling others what the building block does. Before calling a function, the compiler needs to know the return type and parameter type of the function, which is what the declaration does. If you do not declare it before calling the function and the compiler does not know what to do, an error will be reported. However, if the function definition is before being called, the declaration can be omitted.
<code class="c">// 函數(shù)聲明int square_sum(int a, int b); int main() { // ... (調(diào)用square_sum函數(shù)的代碼) ... } // 函數(shù)定義int square_sum(int a, int b) { // ... (函數(shù)體) ... }</code>
Here, int square_sum(int a, int b); is the function declaration. It tells the compiler that the square_sum function receives two integer parameters and returns an integer.
Some pitfalls and suggestions
- Parameter passing: C function parameter passing is value passing, that is, modifying the value of the parameter inside the function will not affect the value of the external variable. If you need to modify the value of an external variable, you can use a pointer.
- Return type: Be sure to pay attention to the return type of the function, especially the function of type void, which does not return any value. If you forget to write the return type, the compiler may return int by default, which may cause unexpected problems.
- Code style: Maintain the consistency of the code style, use meaningful variable names, and add necessary comments, which can improve the readability and maintainability of the code.
- Error handling: Handle possible errors in the function, such as invalid parameters, and return the corresponding error code or information.
In short, understanding function definitions, calls and declarations is the key to writing a good C program. By mastering this knowledge, you can write more elegant and robust C code. Don’t forget to practice more and practice more to truly master these skills. Remember, programming is a craft, and practice makes perfect!
The above is the detailed content of How to define the call declaration format of c language function. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
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
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
What is Ethereum? What are the ways to obtain Ethereum ETH?
Jul 31, 2025 pm 11:00 PM
Ethereum is a decentralized application platform based on smart contracts, and its native token ETH can be obtained in a variety of ways. 1. Register an account through centralized platforms such as Binance and Ouyiok, complete KYC certification and purchase ETH with stablecoins; 2. Connect to digital storage through decentralized platforms, and directly exchange ETH with stablecoins or other tokens; 3. Participate in network pledge, and you can choose independent pledge (requires 32 ETH), liquid pledge services or one-click pledge on the centralized platform to obtain rewards; 4. Earn ETH by providing services to Web3 projects, completing tasks or obtaining airdrops. It is recommended that beginners start from mainstream centralized platforms, gradually transition to decentralized methods, and always attach importance to asset security and independent research, to
How to choose a free market website in the currency circle? The most comprehensive review in 2025
Jul 29, 2025 pm 06:36 PM
The most suitable tools for querying stablecoin markets in 2025 are: 1. Binance, with authoritative data and rich trading pairs, and integrated TradingView charts suitable for technical analysis; 2. Ouyi, with clear interface and strong functional integration, and supports one-stop operation of Web3 accounts and DeFi; 3. CoinMarketCap, with many currencies, and the stablecoin sector can view market value rankings and deans; 4. CoinGecko, with comprehensive data dimensions, provides trust scores and community activity indicators, and has a neutral position; 5. Huobi (HTX), with stable market conditions and friendly operations, suitable for mainstream asset inquiries; 6. Gate.io, with the fastest collection of new coins and niche currencies, and is the first choice for projects to explore potential; 7. Tra
Ethena treasury strategy: the rise of the third empire of stablecoin
Jul 30, 2025 pm 08:12 PM
The real use of battle royale in the dual currency system has not yet happened. Conclusion In August 2023, the MakerDAO ecological lending protocol Spark gave an annualized return of $DAI8%. Then Sun Chi entered in batches, investing a total of 230,000 $stETH, accounting for more than 15% of Spark's deposits, forcing MakerDAO to make an emergency proposal to lower the interest rate to 5%. MakerDAO's original intention was to "subsidize" the usage rate of $DAI, almost becoming Justin Sun's Solo Yield. July 2025, Ethe
What is Binance Treehouse (TREE Coin)? Overview of the upcoming Treehouse project, analysis of token economy and future development
Jul 30, 2025 pm 10:03 PM
What is Treehouse(TREE)? How does Treehouse (TREE) work? Treehouse Products tETHDOR - Decentralized Quotation Rate GoNuts Points System Treehouse Highlights TREE Tokens and Token Economics Overview of the Third Quarter of 2025 Roadmap Development Team, Investors and Partners Treehouse Founding Team Investment Fund Partner Summary As DeFi continues to expand, the demand for fixed income products is growing, and its role is similar to the role of bonds in traditional financial markets. However, building on blockchain
Ethereum (ETH) NFT sold nearly $160 million in seven days, and lenders launched unsecured crypto loans with World ID
Jul 30, 2025 pm 10:06 PM
Table of Contents Crypto Market Panoramic Nugget Popular Token VINEVine (114.79%, Circular Market Value of US$144 million) ZORAZora (16.46%, Circular Market Value of US$290 million) NAVXNAVIProtocol (10.36%, Circular Market Value of US$35.7624 million) Alpha interprets the NFT sales on Ethereum chain in the past seven days, and CryptoPunks ranked first in the decentralized prover network Succinct launched the Succinct Foundation, which may be the token TGE
Solana and the founders of Base Coin start a debate: the content on Zora has 'basic value'
Jul 30, 2025 pm 09:24 PM
A verbal battle about the value of "creator tokens" swept across the crypto social circle. Base and Solana's two major public chain helmsmans had a rare head-on confrontation, and a fierce debate around ZORA and Pump.fun instantly ignited the discussion craze on CryptoTwitter. Where did this gunpowder-filled confrontation come from? Let's find out. Controversy broke out: The fuse of Sterling Crispin's attack on Zora was DelComplex researcher Sterling Crispin publicly bombarded Zora on social platforms. Zora is a social protocol on the Base chain, focusing on tokenizing user homepage and content
What is Zircuit (ZRC currency)? How to operate? ZRC project overview, token economy and prospect analysis
Jul 30, 2025 pm 09:15 PM
Directory What is Zircuit How to operate Zircuit Main features of Zircuit Hybrid architecture AI security EVM compatibility security Native bridge Zircuit points Zircuit staking What is Zircuit Token (ZRC) Zircuit (ZRC) Coin Price Prediction How to buy ZRC Coin? Conclusion In recent years, the niche market of the Layer2 blockchain platform that provides services to the Ethereum (ETH) Layer1 network has flourished, mainly due to network congestion, high handling fees and poor scalability. Many of these platforms use up-volume technology, multiple transaction batches processed off-chain
Top 10 AI concept coins worth paying attention to in 2025 What are the AI concept coins worth paying attention to in 2025
Jul 29, 2025 pm 06:06 PM
The top ten potential AI concept coins in 2025 include: 1. Render (RNDR) as a decentralized GPU rendering network, providing AI with key computing power infrastructure; 2. Fetch.ai (FET) builds an intelligent economy through autonomous economic agents and participates in the formation of the "Artificial Intelligence Super Alliance" (ASI); 3. SingularityNET (AGIX) builds a decentralized AI service market, promotes the development of general artificial intelligence, and is a core member of ASI; 4. Ocean Protocol (OCEAN) solves data silos and privacy issues, provides secure data transactions and "Compute-to-Data" technology to support the AI data economy; 5.
