Thread: question on gets() function

>I've never used this function before
Good, don't start using it.

gets is very buggy, there is a function that fixes the problems of gets called fgets, here's an example that reads a string from the keyboard:

Code:

char array[SIZE];
fgets ( array, sizeof array, stdin );

However, C++ offers the cin.getline function which should be used instead of C functions to be consistent. The effect is the same.

-Prelude

I am no expert at this but hopefully this will help..

Code:

void main()
{
   #define buffersize 80
     char buffer[buffersize];
    cout<<"Enter any sentence:"<<endl;
    cin.getline(buffer, buffersize);
    cout<<buffer<<endl;
}

or if you can use just plain get()

Code:

void main()
{
   char ch;
   int i = 0;
   #define buffersize 80
   char buffer[buffersize] = {'\0'};
   cout<<"Enter any sentence:"<<endl;
   while((ch = cin.get()) != EOF)
   {
      cout.put(ch);
      buffer[i] = ch;
      i++;
   }
   for(int b=0; b != buffersize; b++)
   { cout<<buffer[b];}
   
}

>void main()
Congratulations, your program is undefined starting right here
void main is wrong, main should return an int and nothing else otherwise the result will be undefined (aka illegal).

>while((ch = cin.get()) != EOF)
This won't work, you declared ch as a char yet EOF is a value that can't be held by a char. You also fail to check for boundaries in the loop, so the user could enter any amount of characters and the program will happily write it all to memory that you don't own.

Code:

#include <iostream>
#define buffersize 80
using namespace std;

int main( void )
{
  int ch;
  int i = 0;
  char buffer[buffersize] = {'\0'};
  cout<<"Enter any sentence:"<<endl;
  while((ch = cin.get()) != EOF){
    if ( i == buffersize ) {
      buffer[i] = '\0';
      break;
    }
    cout.put(ch);
    buffer[i++] = ch;
  }
  cout<<buffer;   
  return EXIT_SUCCESS;
}

-Prelude

>That way to don't have to worry about the EOF business.
Can you be asolutely sure that a user will not need to enter a tilde as part of the input? I can be sure that EOF won't be

What type of input is used to end the program is up to the programmer, but consider ease of use as well as whether or not that input could by any stretch of the imagination be valid input. If it does end up being input that the user wants to process at some point, then you've got a broken program.

-Prelude

It'll compile - that doesn't make it right, softcoder...

Prelude's right.

What do mean by "void main()" is illegal

Yeah its not right, See here
Mind you all my course material shows main declared as void(makes me wonder what else they haven't updated). So its no wonder people still use it, I did until I came here.

>while((ch = cin.get()) != EOF)
This won't work, you declared ch as a char yet EOF is a value that can't be held by a char.

you use the exact same line:

while((ch = cin.get()) != EOF)

in your code.

I think you'll find prelude declared ch as int which can hold EOF

int main( void )
{
int ch;
int i = 0;
char buffer[buffersize] = {'\0'};
cout<<"Enter any sentence:"<<endl;
while((ch = cin.get()) != EOF){
if ( i == buffersize ) {
buffer[i] = '\0';
break;
}
cout.put(ch);
buffer[i++] = ch;
}
cout<<buffer;
return EXIT_SUCCESS;
}