What is the difference between Java functions and C language functions?

The main difference between Java and C language functions is: Memory management: Java automatically manages memory, while C requires manual allocation and release of memory. Data types: Java has a strict data type system, while C is relatively weak and can lead to errors. Function signature: Java function signature specifies the return value type, while C only specifies the parameter type. Parameter passing: Java uses passing by reference while C uses passing by value for primitive types. Error handling: Java uses exceptions while C uses errno or function return values ​​to indicate errors.

The difference between Java functions and C language functions

Memory management

• Java: Java uses Automatic memory management, no need to manually allocate and release memory. The garbage collector is responsible for releasing objects when they are no longer needed.
• C: C requires explicit memory management. The programmer is responsible for allocating and releasing memory. Improper management can lead to memory leaks or segfaults.

Data Type

• Java: Java has a strict data type system, each variable must declare its type, such as int, float, String, etc.
• C: C has a weak data type system and variables can be implicitly converted to other types, which can lead to errors.

Function signature

• Java: A Java function signature specifies the function name, parameter types, and return value type.
• C: The C function signature only specifies the function name and parameter types, and the return value type is inferred from the function header.

Parameter passing

• Java: Java functions use reference passing, that is, parameters modified in the function will affect the value in the caller.
• C: C functions use value passing for basic type parameters and use reference passing for non-basic type parameters.

Error handling

• Java: Java uses exceptions to handle errors. Different exceptions represent different error types.
• C: C uses the errno global variable or the return value of a function to indicate errors.

Practical case: Calculate the sum of squares of two numbers

Java code:

public class Main {
    public static long sumOfSquares(long a, long b) {
        return a * a + b * b;
    }

    public static void main(String[] args) {
        long x = 3;
        long y = 4;
        long result = sumOfSquares(x, y);
        System.out.println(result); // 输出 25
    }
}

C code:

#include <stdio.h>

long sumOfSquares(long a, long b) {
    return a * a + b * b;
}

int main() {
    long x = 3;
    long y = 4;
    long result = sumOfSquares(x, y);
    printf("%ld\n", result); // 输出 25
    return 0;
}

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