How to design and implement efficient C++ functions

The key to designing efficient C functions is to avoid unnecessary calls, minimize branching, prioritize memory locality, and optimize with inline functions, constant references, move semantics, and precompiled headers. Practical examples show how to apply these principles to calculate the Fibonacci sequence. Follow these principles and techniques to write efficient functions and improve application performance.

How to design and implement efficient C functions

Preface

In C Writing efficient functions is crucial as it can significantly improve the performance of your application. Efficient functions can be achieved by following best practices and using sound optimization techniques.

Design principles

• Avoid unnecessary function calls: The cost of function calls is very high and should be minimized.
• Minimize branches: Branches can reduce performance and should be limited to what is necessary.
• Avoid deep nesting: Too many levels of nesting will make the code difficult to understand and maintain.
• Prioritize memory locality: Keeping related data close to each other in memory helps improve access speed.

Optimization technology

• Use inline functions: Embed the function code directly into the call point to eliminate the overhead of function calls .
• Use constant references: Pass objects by reference rather than by value to avoid unnecessary copying.
• Use move semantics: Use std::move instead of the copy constructor to move objects efficiently.
• Use precompiled headers: Compile commonly included header files into precompiled headers to reduce compilation time.
• Use optimizing compiler options: Enable compiler optimization options such as O2 and -O3 to improve code performance.

Practical Case

The following is an example of a C function that calculates the Fibonacci sequence, showing how to apply these principles:

// 快速幂取余算法
long long power_mod(long long base, long long exponent, long long modulus) {
  long long result = 1;
  base %= modulus;
  while (exponent > 0) {
    if (exponent % 2 == 1) {
      result = (result * base) % modulus;
    }
    base = (base * base) % modulus;
    exponent >>= 1;
  }
  return result;
}

// 斐波那契数列
long long fibonacci(int n) {
  if (n <= 1) {
    return n;
  }
  return (power_mod(10, n - 2, 1000000007) + power_mod(1, n - 1, 1000000007)) % 1000000007;
}

Conclusion

By following these design principles and leveraging optimization techniques, you can write efficient C functions that improve the overall performance of your application. Continuously practicing and optimizing your code is key to improving function efficiency.

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