计算两个日期间的天数

#include <stdio.h>
int DiJiTian(int year, int month, int day);
int isRunNian(int year);
void swap(int *a, int *b);
int main(){
int year1, month1, day1;
int year2, month2, day2;
int result = 0;

scanf("%d %d %d", &year1, &month1, &day1);
scanf("%d %d %d", &year2, &month2, &day2);
if(year1 == year2)
{result = DiJiTian(year1, month1, day1) - DiJiTian(year2, month2, day2);
if(result < 0)
{
result = 0 - result;
}
}//情况1的代码
else
{
if(year1 > year2){
swap(&year1, &year2);
swap(&month1, &month2);
swap(&day1, &day2);
}
int a, b, c;

if(isRunNian(year1)){
a = 366 - DiJiTian(year1, month1, day1);
}else{
a = 365 - DiJiTian(year1, month1, day1);
}//计算a的代码
b = 0;
for(int i = year1 + 1; i < year2; i++)
{
if(isRunNian(i)){
b += 366;
}else{
b += 365;
}
}  //计算b的代码
c = DiJiTian(year2, month2, day2);
//计算c的代码
result = a + b + c;
//情况2的代码
}
printf("%d\n", result);
return 0;
}
int isRunNian(int year){
int result;
if(year%400 == 0 ||(year%4==0 && year%100!=0)){
result = 1;
} else{
result = 0;
}
return result;
}//判断闰年的函数
int DiJiTian(int year, int month, int day){
int result = 0;
for(int i = 1; i < month; i++){ 	//step1
if(i==1||i==3||i==5||i==7||i==8||i==10||i==12){
result += 31;
} else if (i == 4 || i ==6 || i == 9 || i==11){
result += 30;
} else if(i == 2){
if(isRunNian(year)){
result += 29;
} else {
result += 28;
}
}
}
result += day;	//step2
return result;
}//求解某一日期是当年的第几天的函数
void swap(int *a, int *b){
int e;
e = *a;
*a = *b;
*b = e;
}//交换两个变量的值的函数