How compatible are C++ functions with C language functions?

C is compatible with C language functions, but there are subtle differences in function declarations, parameter overloading, return types, and parameter passing methods. In addition, C provides exception handling mechanisms.

Compatibility of C functions and C language functions

The C language is a superset of the C language, which means that C can Compatible with C language functions. C functions and C language functions are basically called in the same way, but there are some subtle differences.

Function declaration

C function declaration is similar to C language function declaration, but C allows type qualifiers (const, volatile, etc.) to be added after the function name:

C language:

int add(int a, int b);

C language:

int add(const int a, const int b);

Function parameters

C supports function overloading, but C language does not. Therefore C function parameters can have different types and numbers.

Function return type

The return type of a C language function can only be void or a basic type, while a C function can return any type (including classes and structures) .

How to pass parameters

In C language, function parameters are always passed by value, but in C, parameters can be passed by value, reference and pointer. transfer.

Exception handling

The C language does not have an exception handling mechanism, and C supports exception handling, which means that C functions can handle exceptions that occur during function execution.

Practical case

The following is an example of a function that finds the sum of squares implemented in C and C languages:

C language:

#include <stdio.h>

int square_sum(int n) {
  int sum = 0;
  for (int i = 1; i <= n; i++) {
    sum += i * i;
  }
  return sum;
}

int main() {
  int n;
  printf("Enter a number: ");
  scanf("%d", &n);
  printf("The sum of squares from 1 to %d is %d\n", n, square_sum(n));
  return 0;
}

C language:

#include <iostream>

using namespace std;

int square_sum(const int n) {
  int sum = 0;
  for (int i = 1; i <= n; i++) {
    sum += i * i;
  }
  return sum;
}

int main() {
  int n;
  cout << "Enter a number: ";
  cin >> n;
  cout << "The sum of squares from 1 to " << n << " is " << square_sum(n) << endl;
  return 0;
}

In general, C functions are basically compatible with C language functions, but C provides more powerful features, such as Parameter overloading, exception handling and passing by reference.

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