long long 和 long int 有什么区别

long long和long int是C++编程语言中的两种整数数据类型，它们在表示范围和占用内存空间上有一些区别。下面将详细介绍这两种数据类型的特点和使用场景。

cpp
#include 
using namespace std;
long long fibonacci(long long n) {
    if (n <= 1) {
        return n;
    }
    long long a = 0, b = 1;
    for (long long i = 2; i <= n; i++) {
        long long temp = a + b;
        a = b;
        b = temp;
    }
    return b;
}
int main() {
    long long n = 50;
    long long result = fibonacci(n);
    cout << "斐波那契数列第" << n << "项为：" << result << endl;
    return 0;
}

cpp
#include 
using namespace std;
long long sumArray(long long arr[], int size) {
    long long sum = 0;
    for (int i = 0; i < size; i++) {
        sum += arr[i];
    }
    return sum;
}
int main() {
    int size = 1000000;
    long long arr[size];
    for (int i = 0; i < size; i++) {
        arr[i] = i + 1;
    }
    long long result = sumArray(arr, size);
    cout << "数组元素之和为：" << result << endl;
    return 0;
}