Member Avatar for anuragcoder

Hi guys!

I want the user to enter the day, month and year in a dd/mm/yyyy format.
But what i've written doesn't seem to work.

Code:

char d[2];
char m[2];
char y[4];

cout << "Day:";
gets(d);
cout << "Month:";
gets(m);
cout << "Year:";
gets(y);

In the output, it doesn't stop for Day, Goes for month.. and suddenly program crashes at Year. Any Help?

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Dani AI

Generated

As hinted, the crash is almost certainly from writing past the ends of those small C arrays and from using gets(). A string like "31" needs 3 bytes (two digits plus the '\0'), and "2010" needs 5. gets() ignores buffer size, so with char d[2] you invoke undefined behavior and crash. The safe, idiomatic C++ solutions are to read into proper types (ints) or into std::string and parse/validate.

A robust pattern: read the whole line, parse the three numbers and the separators, then validate ranges. This avoids buffer overflows and gives clear error handling.

#include <iostream>
#include <string>
#include <sstream>

int main() {
    std::string line;
    std::cout << "Enter date (dd/mm/yyyy): ";
    if (!std::getline(std::cin, line)) return 0;

    std::istringstream ss(line);
    int d, m, y; char c1, c2;
    if (!(ss >> d >> c1 >> m >> c2 >> y) || c1 != '/' || c2 != '/' || !ss.eof()) {
        std::cerr << "Bad format. Use dd/mm/yyyy\n";
        return 1;
    }

    // validation follows (see function below)
}

Use a small validator that checks month range, day range (with February/leap-year rules), and a sensible year range. Example validator:

bool isLeap(int y) {
    return (y % 4 == 0 && y % 100 != 0) || (y % 400 == 0);
}

bool validDate(int d, int m, int y) {
    if (y < 1 || m < 1 || m > 12) return false;
    int mdays[] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
    if (m == 2 && isLeap(y)) mdays[2] = 29;
    return d >= 1 && d <= mdays[m];
}

Troubleshooting tips: avoid gets() (use std::getline or fgets in C), prefer std::string/std::istringstream or plain int extraction with checks, compile with warnings on (-Wall) and use AddressSanitizer (-fsanitize=address) or Valgrind to catch overruns. If you mix operator>> and std::getline, clear the leftover newline with std::cin.ignore() before reading a line.

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Member Avatar for Ancient Dragon

why are you using character arrays instead of integers?

why are you using C's gets() function instead of c++ cin?

If you really really want to use character arrays then you need to make them larger -- you have to account for the string's NULL terminating character. With integers you don't have to worry about that.

Member Avatar for anuragcoder

Thanks... I've understood...

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