Comparison of the advantages and disadvantages of C++ function parameter passing methods

C Function parameter passing is divided into value passing and reference passing. Value passing does not modify the variables in the function. The advantage is low memory consumption, but the disadvantage is high copy overhead for large data structures. The advantage of passing by reference is that it avoids the copy overhead of large data structures, but the disadvantage is that it may modify the variables in the calling function.

C Function parameter passing method

In C, the function parameter passing method is divided into value passing and are passed by reference . Each method has its advantages and disadvantages, as follows:

Value passing

• Advantages:

  • Variables in the calling function will not be modified
  • Modification of parameters within the function will not affect the value in the calling function
  • Low memory consumption

• Disadvantages:

  • For large data structures, a lot of copy overhead will be generated
  • For basic data types ( Such as int, float, etc.), low efficiency

pass by reference

• Advantages:

  • Avoid the copy overhead of large data structures
  • For basic data types, more efficient

• Disadvantages:

  • Variables in the calling function may be modified
  • Need to be careful to avoid dangling references

Practical case

Value transfer

void swapVal(int a, int b) {
  int temp = a;
  a = b;
  b = temp;
}

int main() {
  int x = 5, y = 10;
  swapVal(x, y);  // 调用函数，值传递
  cout << "x: " << x << ", y: " << y << endl;  
}

Output:

x: 5, y: 10

Reference transfer

void swapRef(int &a, int &b) {
  int temp = a;
  a = b;
  b = temp;
}

int main() {
  int x = 5, y = 10;
  swapRef(x, y);  // 调用函数，引用传递
  cout << "x: " << x << ", y: " << y << endl;
}

Output:

x: 10, y: 5

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