C :

#include<stdio.h>
int main()
{
	int a,b,c,t;
	t=0;
	scanf("%d-%d-%d",&a,&b,&c);
	if(b==1)
	{
       t=0;
	}
	else if(b==2)
	{
	   t=31;
	}
	else if(b==3)
	{
	   t=31+28; 	
	}
	else if(b==4)
	{
	   t=31+28+31; 	
	}
	else if(b==5)
	{
	   t=31+28+31+30; 	
	}
	else if(b==6)
	{
	   t=31+28+31+30+31; 	
	}
	else if(b==7)
	{
	   t=31+28+31+30+31+30; 	
	}else if(b==8)
	{
	   t=31+28+31+30+31+30+31; 	
	}else if(b==9)
	{
	   t=31+28+31+30+31+30+31+31; 	
	}else if(b==10)
	{
	   t=31+28+31+30+31+30+31+31+30; 	
	}else if(b==11)
	{
	   t=31+28+31+30+31+30+31+31+30+31; 	
	}
	else if(b==12)
	{
	   t=31+28+31+30+31+30+31+31+30+31+30; 	
	}
    t=t+c;
	if(a%4==0&&a%100!=0||a%400==0)
	{
		if(b>2)
		{
			t = t+1; 
		}
	 }
	 printf("%d\n",t);
	  
}

C++ :

#include<stdio.h>
int main()
{
    int a,b,c,t;
    t=0;
    scanf("%d-%d-%d",&a,&b,&c);
    if(b==1)
    {
        t=0;
    }
    else if(b==2)
    {
        t=31;
    }
    else if(b==3)
    {
        t=31+28;
    }
    else if(b==4)
    {
        t=31+28+31;
    }
    else if(b==5)
    {
        t=31+28+31+30;
    }
    else if(b==6)
    {
        t=31+28+31+30+31;
    }
    else if(b==7)
    {
        t=31+28+31+30+31+30;
    }
    else if(b==8)
    {
        t=31+28+31+30+31+30+31;
    }
    else if(b==9)
    {
        t=31+28+31+30+31+30+31+31;
    }
    else if(b==10)
    {
        t=31+28+31+30+31+30+31+31+30;
    }
    else if(b==11)
    {
        t=31+28+31+30+31+30+31+31+30+31;
    }
    else if(b==12)
    {
        t=31+28+31+30+31+30+31+31+30+31+30;
    }
    t=t+c;
    if(a%4==0&&a%100!=0||a%400==0)
    {
        if (b > 2)
        {
          t = t+1;  
        }
         
    }
    printf("%d\n",t);
}
     
 
 

Java :

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
        // 解析输入的日期
        String[] parts = input.split("-");
        int year = Integer.parseInt(parts[0]);
        int month = Integer.parseInt(parts[1]);
        int day = Integer.parseInt(parts[2]);

        // 计算当天是这一年的第几天
        int dayOfYear = day + daysInPreviousMonths(month, year);

        // 输出结果
        System.out.println(dayOfYear);
    }

    // 计算指定月份之前的所有天数
    private static int daysInPreviousMonths(int month, int year) {
        int[] daysInMonth = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
        int days = 0;

        // 判断是否为闰年
        if (isLeapYear(year)) {
            daysInMonth[2] = 29;
        }

        for (int i = 1; i < month; i++) {
            days += daysInMonth[i];
        }
        return days;
    }

    // 判断是否为闰年
    private static boolean isLeapYear(int year) {
        return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
    }
}

Python :

# coding=utf-8
#python2
m = [31,28,31,30,31,30,31,31,30,31,30,31]
a,b,c = map(int,raw_input().split('-'))
s = 0
if a%4==0 and a%100!=0 or a%400==0:
    m[1] = 29
for i in range(b-1):
    s += m[i]
s += c
print(s)

C# :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    internal class Program
    {
        static void Main()
        {
            int r = 0;
            int[] days = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
            string[] O  = Console.ReadLine().Split('-');
            int year =Convert.ToInt16( O[0]);
            int m = Convert.ToInt16(O[1]);
            int d = Convert.ToInt16(O[2]);
            if ( (year%4==0 && year%100!=0 )|| year%400==0 ) {
                days[1] += 1;
                for (int i = 0; i < m-1; i++) {
                r += days[i];
                }
               
                
            }
            else
            {
                for (int i = 0; i < m - 1; i++)
                {
                    r += days[i];
                }
            }
            r += d;
            Console.WriteLine(r);
            Console.ReadKey();
     
        }
    }
}