C语言根据日期取其位于一年中的第几天

#include <iostream>#include <stdlib.h>using namespace std;bool isLeapYear( int iYear ){//判断闰年if( iYear < 0 )return false;if( !(iYear % 400) )return true;if( !( iYear % 100 ))return false;if( !( iYear % 4 ) )return true;return false;}int GetDayInYear( int iYear, int iMonth, int iDay ){//成功则返回1-366中的一个数失败则返回-1if( iYear < 0 )return -1;if( iMonth > 13 || iMonth < 1 )return -1;const int leapYear[12] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };const int noLeapYear[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };int i;int iCurMonth = iMonth - 1;int iIndex = 0;if( isLeapYear( iYear ) ){//闰年for( i = 0; i < iCurMonth; i++ ){iIndex += leapYear[i];}if( iDay > leapYear[i] || iDay < 1 )return -1;iIndex += iDay;}else{for( i = 0; i < iCurMonth; i++ ){iIndex += noLeapYear[i];}if( iDay > noLeapYear[i] || iDay < 1 )return -1;iIndex += iDay;}return iIndex;}int main( int argc, char* argv[] ){printf( "Day in Year: %d\n" ,GetDayInYear( 2000, 2, 30 ) );return 0;}