Best practices for using C++ inline functions in large programs

Best practice: Suitable for functions that are small and computationally simple. Suitable for frequently called functions. Avoid inlining in loops. Avoid pointers and references. Use appropriate inline keywords (inline/__inline). Practical case: Inline function to calculate the greatest common divisor of two numbers: inline int gcd(int a, int b) { if (b == 0) return a; return gcd(b, a % b); }

C Best practices for using inline functions in large programs

Inline functions are functions that the compiler converts into Embed directly into the location where it is called, rather than being called like a normal function. In large programs, rational use of inline functions can significantly improve program execution efficiency.

Best Practice

• Small and simple functions: Only functions that are small and computationally simple are suitable as inline functions . Complex functions can make code difficult to read and maintain.
• Frequently called functions: Inlining only has a significant effect on frequently called functions. For functions that are called less often, the benefit from inlining may be small.
• Avoid inlining in loops: Inlining functions within loops can cause code bloat, negating the benefits of inlining.
• Avoid using pointers and references: Using pointers and references in inline functions may make compiler optimization more difficult, thereby reducing the effect of inlining.
• Use appropriate inline keywords: C provides two inline keywords, inline and __inline. inline is an inline directive in standard C, while __inline is an extended keyword in GNU C that may be more efficient in certain compiler versions.

Practical case

Suppose we want to write a function that calculates the greatest common divisor of two numbers. This function has a small amount of calculation and is frequently called in the program. It is very suitable for use as an inline function:

inline int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}

Summary

Reasonable use of inline functions can improve Execution efficiency of large C programs. It's important to follow best practices and use real-world examples to understand how to use inline functions effectively.

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