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I'm trying to initialize the last element in the array

int grades[10];

to grade 7 but it doesn't seem to work

I'm using C++ btw

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    @JohnHemmars: since you're new to C++, sometimes your notion of certain things ("last element" in your case) doesn't coincide with the common one. Please, try posting more complete examples, preferably the ones that can be copy-pasted and immediately compiled. Commented Sep 1, 2009 at 21:52

5 Answers 5

Reset to default
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If you want to initialize them all at definition:

int grades[10] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 7 };

If you want to initialize after:

int grades[10];
grades[9] = 7;

But, be aware that grades 0..8 will still be uninitialized, and will likely be junk values.

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Thanks, I forgot that the ninth element was the last one =) thank you
if you were assigning to grades[10] that's called an "off by one" error. That is memory that grades doesn't own and you may have corrupted something else in the function/program. en.wikipedia.org/wiki/Off-by-one_error
yeah thank you very much, I knew about this but I've never really used it while coding.. I won't forget it from now on!
You're incorrect in that the "ninth" one is last. If you have ten elements, the tenth one is the last one. The thing is that they are numbered 0 through 9, so your tenth element is accessed by the number 9.
@tfinniga: You mean definition, not declaration, since int grades[10]; defines the array.
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One more thing, if you initialize only the first element (if explicit array size is specified) or a shorter initiliazation list, the unspecified elements are fill with 0. E.g.

int grades[10] = {8}; //init with one element

is the same as:

int grades[10] = { 8, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

or

int grades[10] = { 1, 9, 6, 16 }; //or init with a shorter than array size list with a minimum of 1 element

is the same as:

int grades[10] = { 1, 9, 6, 16, 0, 0, 0, 0, 0, 0 };

I find it handy for initializing an array with 0 values.

float coefficients[10] = {0.0f}; //everything here is full of 0.0f
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Note that it is valid C++ to write: int a[10] = {};.
I would be careful about assuming the contents of an array will be zeroed by default. This is compiler and platform specific.
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when You write something like 

int a[5] = {0};

it sets the whole array to zero on the contrary 

int a[5] = {3};

sets only the first element and the rest may be anything(garbage values);

if You want to set the whole array with some value then u can go for the 

std :: fill()

something like this

std::fill(arr, arr+100, 7); // sets every value in the array to 7

and if there is a character array You can always go for the memset function

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The last element is grades[9], since arrays in C++ are zero-based (e.g. grades[0] to grades[9] are 10 elements). Is that what you're doing?

You might need to subtract one from the grade to use as your subscript value, or set the extent to one more.

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Remember that an array with ten elements will have grades[0] through grades[9], and that grades[10] is an error.

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