Check if a date is valid or not in C?

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Check if a date is valid or not in C?

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#1 by (1 votes)
#2 by (-1 votes)

1

I need to check whether a date is valid in C, and for this I will have a function called verificarData that will be passed to it by the user input and will check whether or not it is a valid date.

But I'm in doubt, because I'll have to break this data to see if it contains:

If it contains two bars between the date


If the day is between 1 and 31.



If the month is between 1 and 12.



Year is in the 1900 to 2100 range



If month is 04, 06, 09 or 11, day can be at most 30;


If month is 02, day can be at most 28;

If leap year and month is 02, day can be at most 29.

Which is better to use in case? Use vetor or even char and try to break the date and do the checks, and if I can use with char, how to break it in pieces to check?

For example, if the user enters the following value:

Input : 20/03/2009

How can I break so I can stay, 20/ , 03/ and 2009 separated so I can check?

I also need to check if the day, month and year are numeric, but since I am putting bars with numbers I can not use the isdigit function to check.

Example:

if(isdigit(data)) {
printf("São numéricos.");
}
else {
printf("Não são numéricos.");
}

But it returns as the numbers are not even the user putting the day, month and year with numbers, because because of the bars, it returns as if it were a string. How can I check and return by saying whether or not they are numbers correctly?

c

asked by anonymous 16.06.2017 / 23:16

2 answers

-1

Hello

I made a simple example of how to validate data using if () The user makes the input, the function, verifies that the data is correct; I hope I have helped with an example

#include <stdio.h>

int main()
{
    int dd, mm, yy;

    printf("Enter date (DD/MM/YYYY format): ");
    scanf_s("%d/%d/%d", &dd, &mm, &yy);

    //check year
    if (yy >= 1900 && yy <= 9999)
    {
        //check month
        if (mm >= 1 && mm <= 12)
        {
            //check days
            if ((dd >= 1 && dd <= 31) && (mm == 1 || mm == 3 || mm == 5 || mm == 7 || mm == 8 || mm == 10 || mm == 12))
                printf("Date is valid.\n");
            else if ((dd >= 1 && dd <= 30) && (mm == 4 || mm == 6 || mm == 9 || mm == 11))
                printf("Date is valid.\n");
            else if ((dd >= 1 && dd <= 28) && (mm == 2))
                printf("Date is valid.\n");
            else if (dd == 29 && mm == 2 && (yy % 400 == 0 || (yy % 4 == 0 && yy % 100 != 0)))
                printf("Date is valid.\n");
            else
                printf("Day is invalid.\n");
        }
        else
        {
            printf("Month is not valid.\n");
        }
    }
    else
    {
        printf("Year is not valid.\n");
    }

    return 0;
}

17.06.2017 / 18:19

How to store images in Parse? Alignment of images with inputs

score 1 · Accepted Answer

For example, if the user enters the following value:

Input : 20/03/2009

How can I break so I can stay, 20/ , 03/ and 2009 separated so I can check?

Roles

Use the functions below.

strtok - breaks a string in tokens, given a specific delimiter (use / ).
strtol - converts a string to a long integer.
strstr - finds the first occurrence of a specific substring in a string (use // ).
isdigit - checks if the character passed as an argument is a digit .

Logic

Base the code below. Also see working online here .

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int verificarNumero(char *entrada) {
  int i;

  for (i = 0; entrada[i] != '#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int verificarNumero(char *entrada) {
  int i;

  for (i = 0; entrada[i] != '%pre%'; i++)
  {
    if (entrada[i] != '/' && !isdigit(entrada[i]))
    {
      return 0;
    }
  }

  return 1;
}

int verificarData(char *entrada)
{
  const char substring[3] = "//";

  if (strstr(entrada, substring) != NULL)
  {
    return 0;
  }

  if (verificarNumero(entrada))
  {
    printf("São numéricos.\n");
  }
  else
  {
    printf("Não são numéricos.\n");
    return 0;
  }

  int i = 0;
  long data[3];
  const char delimitador[2] = "/";
  char *token = strtok(entrada, delimitador);

  // Alimenta o vetor de inteiros
  while (token != NULL)
  {
    data[i++] = strtol(token, NULL, 10);
    token = strtok(NULL, delimitador);
  }

  // Realize suas validações. Se alguma não for atingida, retorne '0'

  printf("Dia: %d\n", data[0]);
  printf("Mes: %d\n", data[1]);
  printf("Ano: %d\n", data[2]);

  // Caso contrário, retorne '1'

  return 1;
}

int main()
{
  char str[80];

  printf("Digite uma data: ");
  gets(str);

  printf("%d\n", verificarData(str));

  return(0);
}
'; i++)
  {
    if (entrada[i] != '/' && !isdigit(entrada[i]))
    {
      return 0;
    }
  }

  return 1;
}

int verificarData(char *entrada)
{
  const char substring[3] = "//";

  if (strstr(entrada, substring) != NULL)
  {
    return 0;
  }

  if (verificarNumero(entrada))
  {
    printf("São numéricos.\n");
  }
  else
  {
    printf("Não são numéricos.\n");
    return 0;
  }

  int i = 0;
  long data[3];
  const char delimitador[2] = "/";
  char *token = strtok(entrada, delimitador);

  // Alimenta o vetor de inteiros
  while (token != NULL)
  {
    data[i++] = strtol(token, NULL, 10);
    token = strtok(NULL, delimitador);
  }

  // Realize suas validações. Se alguma não for atingida, retorne '0'

  printf("Dia: %d\n", data[0]);
  printf("Mes: %d\n", data[1]);
  printf("Ano: %d\n", data[2]);

  // Caso contrário, retorne '1'

  return 1;
}

int main()
{
  char str[80];

  printf("Digite uma data: ");
  gets(str);

  printf("%d\n", verificarData(str));

  return(0);
}