garbage value ?

[gowswan]

i am learning "c".i am in the beginning level. i want more explanations about arrays. in arrays what does the garbage means? how it affect the program.

[jwenting]

garbage?
If you haven't initialised array elements or incorrectly declared an array the data in it will be the data that was in the memory spots before the array even existed.

If you change it you can cause the computer to crash...

[1o0oBhP]

an array is essentially a variable which can store a number of values, all stored one after another in memory and all having a certain index;
eg

int numbers[10]; // array of 10 integers, unitialised
int morenumbers[3] = { 27, 4, 1 }; // array of 3 numbers, initialised
int numbers2 [] = { 0, 1, 14, 25 }; // array of 4 numbers, initialised (the [] means the compiler determines the size, in this case 4 as we have asked for 4 numbers

numbers2 is the variable name.
*numbers2 is a pointer to the first in the list (therefore the variable name refers to the head of the array)

Each item can be retreived using the [] operator;

numbers2[0] = 0 // note, the first element is index 0!!
numbers2[1] = 1
numbers2[2] = 14
ect...

arrays can be initialised after they are declared and the best method is a loop eg:

int numbers[5]; // array
char *str; // input string

for(int i = 0; i < 5; i++) // goes from 0 to 4 (as arrays start at 0)
{
    cout << "Enter number " << i << " for the array";
    cin >> str;
    data = atoi(str);
    numbers[i] = data;
}

this code will ask the user to input 5 values, which are inserted into the array.

[Dave Sinkula]

int numbers[5]; // array
char *str; // input string

for(int i = 0; i < 5; i++) // goes from 0 to 4 (as arrays start at 0)
{
    cout << "Enter number " << i << " for the array";
    cin >> str;
    data = atoi(str);
    numbers[i] = data;
}

That's not a string -- you just did a Bad Thing.

[chound]

its a pointer no need to init the number of chars, saves a lot of work.

[jwenting]

when using C++ you should never use char* for strings, instead use <string> which yields the string class.
You can then convert those to char* where needed.

I agree that char* is usually a better idea than char[] to handle strings in C.

[anastacia]

u get garbage values when u have not initialised your variables or arrays inthis case. because when your compiler aloocates a memory space to your array that space may already contain values- hence garbage values

[1o0oBhP]

or even easier...

int numbers[5]; // array

for(int i = 0; i < 5; i++) // goes from 0 to 4 (as arrays start at 0)
{
    cout << "Enter number " << i << " for the array";
    cin >> numbers[i] = data;
}

needs error checking though :)