Get yesterday’s day and date in C programming

In this tutorial, we will learn how to get or find the yesterday’s day and date in C programming.

Here I am using time.h header library.

I will first show you how to find yesterday’s exact date. Then we can easily get the day. ( Like Sunday or Monday or Tuesday etc )

#include <stdio.h>
#include <time.h>

int main() {
    // Get current time
    time_t now = time(NULL);

    // Convert it to local time structure
    struct tm today = *localtime(&now);

    // Subtract one day (24 hours) from the current time
    today.tm_mday -= 1;

    // Normalize the time structure in case of underflow
    mktime(&today);

    // Print yesterday's date in the format DD-MM-YYYY
    printf("Yesterday's date: %02d-%02d-%04d\n", today.tm_mday, today.tm_mon + 1, today.tm_year + 1900);

    return 0;
}

Output:

Yesterday's date: 08-09-2024

I am running it on 9th September so I am getting this output.

You can easily change the date format as well.

To get DD-MM-YYYY this date format I am using: today.tm_mday, today.tm_mon + 1, today.tm_year + 1900

You can change the positions to change the date format.

Get yesterday’s day and date both in C

#include <stdio.h>
#include <time.h>

int main() {
    // Array of day names
    char* daysOfWeek[] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
    
    // Get current time
    time_t now = time(NULL);
    
    // Convert it to local time structure
    struct tm today = *localtime(&now);
    
    // Subtract one day (24 hours) from the current time
    today.tm_mday -= 1;
    
    // Normalize the time structure in case of underflow
    mktime(&today);
    
    // Print yesterday's day and date in the format Day, DD-MM-YYYY
    printf("Yesterday was %s, %02d-%02d-%04d\n", daysOfWeek[today.tm_wday], today.tm_mday, today.tm_mon + 1, today.tm_year + 1900);
    
    return 0;
}

Output:

Yesterday was Sunday, 08-09-2024

If you need anything else do let me know in the comment section below.