What Are Dates and Times in C++
Computers represent dates and times using numerical values that count the passage of time from a fixed starting point, known as the epoch. In most systems, this epoch is set to January 1, 1970, 00:00:00 UTC.
The time_t type is used to store the number of seconds that have elapsed since this epoch, making it a simple and efficient way to measure and compare points in time. However, humans typically think about time in terms of years, months, days, and so on. To bridge this gap, C++ provides the struct tm structure, which breaks down a time value into its individual components (such as year, month, day, hour, minute, and second) for easier formatting and manipulation.
main.cpp
12345678910#include <iostream> #include <ctime> int main() { time_t currentTime; currentTime = time(nullptr); // Get time as seconds since epoch std::cout << "Current time (seconds since epoch): " << currentTime << std::endl; return 0; }
The time_t variable in this example holds the number of seconds that have passed since the system's epoch. This value is obtained from the system clock and is useful for measuring durations, comparing times, or converting to more human-readable formats. Since time_t is just a count of seconds, it does not directly provide calendar information like the current year or month.
main.cpp
12345678910111213141516171819202122#include <iostream> #include <ctime> int main() { std::tm myTime{}; myTime.tm_year = 2023 - 1900; // Years since 1900 myTime.tm_mon = 5; // Months since January (0-11) myTime.tm_mday = 15; // Day of the month (1-31) myTime.tm_hour = 14; // Hours since midnight (0-23) myTime.tm_min = 30; // Minutes after the hour (0-59) myTime.tm_sec = 0; // Seconds after the minute (0-60) std::cout << "Custom date and time: " << (myTime.tm_year + 1900) << "-" << (myTime.tm_mon + 1) << "-" << myTime.tm_mday << " " << myTime.tm_hour << ":" << myTime.tm_min << ":" << myTime.tm_sec << std::endl; return 0; }
The fields of struct tm represent different parts of a calendar date and time. For example, tm_year is the number of years since 1900, so to get the actual year, you add 1900. tm_mon is the number of months since January, ranging from 0 (January) to 11 (December). Other fields like tm_mday, tm_hour, tm_min, and tm_sec represent the day of the month, hour, minute, and second, respectively. By setting these fields, you can specify or manipulate exact dates and times in your program.
The struct tm structure is especially useful when you need to break down a time_t value into its components for tasks such as displaying the date and time in a readable format or performing calendar calculations.
Takk for tilbakemeldingene dine!
Spør AI
Spør AI
Spør om hva du vil, eller prøv ett av de foreslåtte spørsmålene for å starte chatten vår
Fantastisk!
Completion rate forbedret til 11.11What Are Dates and Times in C++
Sveip for å vise menyen
Computers represent dates and times using numerical values that count the passage of time from a fixed starting point, known as the epoch. In most systems, this epoch is set to January 1, 1970, 00:00:00 UTC.
The time_t type is used to store the number of seconds that have elapsed since this epoch, making it a simple and efficient way to measure and compare points in time. However, humans typically think about time in terms of years, months, days, and so on. To bridge this gap, C++ provides the struct tm structure, which breaks down a time value into its individual components (such as year, month, day, hour, minute, and second) for easier formatting and manipulation.
main.cpp
12345678910#include <iostream> #include <ctime> int main() { time_t currentTime; currentTime = time(nullptr); // Get time as seconds since epoch std::cout << "Current time (seconds since epoch): " << currentTime << std::endl; return 0; }
The time_t variable in this example holds the number of seconds that have passed since the system's epoch. This value is obtained from the system clock and is useful for measuring durations, comparing times, or converting to more human-readable formats. Since time_t is just a count of seconds, it does not directly provide calendar information like the current year or month.
main.cpp
12345678910111213141516171819202122#include <iostream> #include <ctime> int main() { std::tm myTime{}; myTime.tm_year = 2023 - 1900; // Years since 1900 myTime.tm_mon = 5; // Months since January (0-11) myTime.tm_mday = 15; // Day of the month (1-31) myTime.tm_hour = 14; // Hours since midnight (0-23) myTime.tm_min = 30; // Minutes after the hour (0-59) myTime.tm_sec = 0; // Seconds after the minute (0-60) std::cout << "Custom date and time: " << (myTime.tm_year + 1900) << "-" << (myTime.tm_mon + 1) << "-" << myTime.tm_mday << " " << myTime.tm_hour << ":" << myTime.tm_min << ":" << myTime.tm_sec << std::endl; return 0; }
The fields of struct tm represent different parts of a calendar date and time. For example, tm_year is the number of years since 1900, so to get the actual year, you add 1900. tm_mon is the number of months since January, ranging from 0 (January) to 11 (December). Other fields like tm_mday, tm_hour, tm_min, and tm_sec represent the day of the month, hour, minute, and second, respectively. By setting these fields, you can specify or manipulate exact dates and times in your program.
The struct tm structure is especially useful when you need to break down a time_t value into its components for tasks such as displaying the date and time in a readable format or performing calendar calculations.
Takk for tilbakemeldingene dine!
