/* Defective Solution in C */
// converts the time represented by the tm structure pointed to by tmP into a calendar time 
(the number of seconds since 00:00:00 UTC, January 1, 1970) 
See: http://www.cplusplus.com/reference/ctime/tm/
static time_t tm_to_time( struct tm* tmP )
{
    time_t result;
    // monthtab[i] is the number of days in the months prior to i 
    static int monthtab[12] = {
	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

    result = ( tmP->tm_year - 70 ) * 365;
    result += ( tmP->tm_year - 69 ) / 4;
    result += monthtab[tmP->tm_mon];
    result += tmP->tm_mday - 1;	// 1-based field 
    result = result * 24 + tmP->tm_hour;    
    result = result * 60 + tmP->tm_min;
    result = result * 60 + tmP->tm_sec;
    return result;
    }






/* Defective Solution in pseudocode */
// converts the time represented by the tm structure pointed to by tmP into a calendar time 
(the number of seconds since 00:00:00 UTC, January 1, 1970) 
static time_t tm_to_time( struct tm* tmP )
{
    time_t result;
    // monthtab[i] is the number of days in the months prior to i 
    static int monthtab[12] = {
	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

    // CONVERT the number of years since the start of the epoch into days. 
    // ADD the number of leap days that have occurred in previous years. 
    // ADD the number of days in the months before this one 
    // ADD the number of days since the beginning of this month. 
    // CONVERT days to hours and add the current hours 
    // CONVERT the hours to minutes and add the current minutes  
    // CONVERT the minutes to seconds and add the current seconds     
    // Return the result 
    }







/* Correct solution */
// converts the time represented by the tm structure pointed to by tmP into a calendar time 
(the number of seconds since 00:00:00 UTC, January 1, 1970) 
static time_t tm_to_time( struct tm* tmP )
{
    time_t result;
    // monthtab[i] is the number of days in the months prior to i 
    static int monthtab[12] = {
	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

    // CONVERT the number of years since the start of the epoch into days. 
    result = ( tmP->tm_year - 70 ) * 365;
    // ADD the number of leap days that have occurred in previous years. 
    result += ( tmP->tm_year - 69 ) / 4;
    // ADD the number of days in the months before this one 
    result += monthtab[tmP->tm_mon];
    // IF we are past February and this year is a leap year THEN
    if ( tmP->tm_mon >= 2 && is_leap( tmP->tm_year + 1900 ) )
    {
       // ADD one
       ++result;
    }   
	// END IF
    // ADD the number of days since the beginning of this month. 
    result += tmP->tm_mday - 1;	// 1-based field 

    // CONVERT days to hours and add the current hours 
    result = result * 24 + tmP->tm_hour;    
    // CONVERT the hours to minutes and add the current minutes  
    result = result * 60 + tmP->tm_min;
    // CONVERT the minutes to seconds and add the current seconds     
    result = result * 60 + tmP->tm_sec;
    // Return the result 
    return result;
    }