c++ char array size validation

Question

I have a character array that can hold 1000 elements (+1 for the '\0'). The array will be filled by user input. I was wondering if there is any way of checking if the input is more than what the array can hold. If I do try to add it, the program will crash before I can compare its size. I was thinking expand the array and see if the input is less than 1000 characters, but that idea doesn't seem like a really good one too me.

EDIT:

im using std::cin.getline() to get input from the user and can't use the Sting class

How are you filling the array? Please give your example

Mark Lakata
– Mark Lakata

2013-10-07 19:53:15 +00:00
Commented Oct 7, 2013 at 19:53 — Mark Lakata
– Mark Lakata, Commented Oct 7, 2013 at 19:53

CS Pei · Accepted Answer · 2013-10-07 20:02:24Z

1

I think one way to check it is to find the index of \0 in your array. If the position is equal or greater than 1000, then you should not add more chars to it.

If you are using cin.getline() you can use a variable n to specify the maximum of chars you want

istream& getline (char* s, streamsize n );
istream& getline (char* s, streamsize n, char delim );

Here you can set n=1001 (it also counts the termination char \0).

edited Oct 7, 2013 at 20:02

answered Oct 7, 2013 at 19:54

CS Pei

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3 Comments

Josip Dorvak Over a year ago

I'm using cin.getline() so all the input is immediatly stored in the array. It's not too important but It's for an assignment and my prof loves slashing 60% off anything that he can find wrong.

juanchopanza Over a year ago

@JosipDorvak You could just use std::string.

Josip Dorvak Over a year ago

Ok i wasn't sure it counted the termination character I'll try it out. Thanks :)

Zac Howland · Accepted Answer · 2013-10-07 20:03:59Z

1

Short answer: yes.

Use std::string:

std::string line
while (std::getline(std::cin, line))
{
    // do something with line
}

If you are not allowed to use std::string, then you can either role your own string class, or look at common implementations of std::getline and mimic them (just without storing it in a std::string).

edited Oct 7, 2013 at 20:03

answered Oct 7, 2013 at 19:58

Zac Howland

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2 Comments

Josip Dorvak Over a year ago

Thanks for the suggestion. I know an actual string would work. But our prof doesn't want us using strings. Really inconvenient. I'm just being overly protected no that he may "try" to overflow the array

John Over a year ago

Of course he's going to try to overflow the array. That is probably one of the major points of this assignment.

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