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Age Calculator (C program to calculate age)

Age Calculator: This program will read your date of birth and print the current age. The logic is behind to implement this program - Program will compare given date with the current date and print how old are you?

Problem Statement

Input date of birth of a person, write a C program to calculate his/her age till the current date in number of years, months, and days.

Age Calculator Program in C

Below is the code of C language to calculate age of the person:

/*Age Calculator (C program to calculate age).*/

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

/*check given year is leap year or not*/
int isLeapYear(int year, int mon) {
  int flag = 0;
  if (year % 100 == 0) {
    if (year % 400 == 0) {
      if (mon == 2) {
        flag = 1;
      }
    }
  } else if (year % 4 == 0) {
    if (mon == 2) {
      flag = 1;
    }
  }
  return (flag);
}

int main() {
  int DaysInMon[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  int days, month, year;
  char dob[100];
  time_t ts;
  struct tm *ct;

  /* enter date of birth */
  printf("Enter your date of birth (DD/MM/YYYY): ");
  scanf("%d/%d/%d", &days, &month, &year);

  /*get current date.*/
  ts = time(NULL);
  ct = localtime(&ts);

  printf("Current Date: %d/%d/%d\n", ct->tm_mday, ct->tm_mon + 1,
         ct->tm_year + 1900);

  days = DaysInMon[month - 1] - days + 1;

  /* leap year checking*/
  if (isLeapYear(year, month)) {
    days = days + 1;
  }

  /* calculating age in no of days, years and months */
  days = days + ct->tm_mday;
  month = (12 - month) + (ct->tm_mon);
  year = (ct->tm_year + 1900) - year - 1;

  /* checking for leap year feb - 29 days */
  if (isLeapYear((ct->tm_year + 1900), (ct->tm_mon + 1))) {
    if (days >= (DaysInMon[ct->tm_mon] + 1)) {
      days = days - (DaysInMon[ct->tm_mon] + 1);
      month = month + 1;
    }
  } else if (days >= DaysInMon[ct->tm_mon]) {
    days = days - (DaysInMon[ct->tm_mon]);
    month = month + 1;
  }

  if (month >= 12) {
    year = year + 1;
    month = month - 12;
  }

  /* print age */
  printf("\n## Hey you are  %d years %d months and %d days old. ##\n", year,
         month, days);

  return 0;
}

Output

RUN 1:
Enter your date of birth (DD/MM/YYYY): 17/09/1992
Current Date: 17/9/2024

## Hey you are  32 years 0 months and 1 days old. ##

RUN 2:
Enter your date of birth (DD/MM/YYYY): 15/03/1998
Current Date: 17/9/2024

## Hey you are  26 years 6 months and 4 days old. ##

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