What datatype can be used for array index 0 to 4000000 when i used int or unsigned long long my program crashes

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For finding the even number of fibonnaci series

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int a[4000000];
    int sum=0;
    int i;
    for(i=0;i<4000000;i++)
    {
       if(i==0)
       {
           a[0]=1;
       }
       else if(i==1)
       {
           a[1]=2;
       }
       else
       {
           a[i]=a[i-1]+a[i-2];
       }
       if(a[i]%2==0)
       {
           sum+=a[i];
       }
    //printf("a[%d]=%d\n",i,a[i]);
    }
    printf("sum=%d\n",sum);//
    return 0;
}

This code crashes when i compile.But for a=10 this code works just fine. I tried changing the type to unsigned long long and format specifier to %llu still the code crashes even when i changed the main datatype to unsigned long long it is not working i thought the number 4000000 is too big for int type but when i searched i got this code from other user in his website which is

// Simple Program to print Fibonacci series in Console
#include <stdio.h>
int main() {
    int x=1,y=2,sum=0,limit=0,i=0,temp=0;
    printf("Enter Limit:");
    scanf("%d",&limit);

    if(limit==1)
        printf("%d",x);
    else if(limit>1) {
        printf("%d %d",x,y);
        if (limit>2) {
            while (i<limit-2) {
                temp=y;
                sum=x+y;
                x=temp;
                y=sum;
                printf(" %d",sum);
                i++;
            }
        }
    }      
    printf("\n");
    return 0;
 }

this code works just fine I am a beginner and a self taught i don't know what is wrong with my code is it because i used an array.Please help to rectify this. Thank you.


Most implementations have a fairly small limit on the size of stack frames. If you need a large array, make it static or allocate it dynamically.

static int a[4000000];

c, I tried changing the type to unsigned long long and format specifier to %llu still the A stack has limited size so creating a huge array as a local variable will int* a = malloc(4000000 * sizeof *a); if (a == NULL) { // no more There will be integer overflow in the calculations and your result will be wrong. In the following example, integers equal to 4,294,967,296 that are represented as decimal, hexadecimal, and binary literals are assigned to Long values. Dim longValue1 As Long = 4294967296 Console.WriteLine(longValue1) Dim longValue2 As Long = &H100000000 Console.WriteLine(longValue2) Dim longValue3 As Long =


On most systems local variables are allocated on the stack. A stack has limited size so creating a huge array as a local variable will overflow the stack.

Instead use dynamic memory like:

int* a = malloc(4000000 * sizeof *a);
if (a == NULL)
{
    // no more memory
    exit(1);
}

// Now a can be used as an array, e.g. a[1234] = 42

... put your code here


// When done, deallocate memory like:
free(a);

That said - there is no point in using an array that huge. Simple integer types can't hold the values for that many Fibonacci numbers. There will be integer overflow in the calculations and your result will be wrong. You can check this by using int a[100]; and then print the calculated values. You'll soon see that they are wrong.

C array index, signed or unsigned - Keil forum, "I can't declare an array of 65530 chars because 65530 isn't a valid int. Unsuffixed hex or octal: int, unsigned int, long int, unsigned long int" Depending on where you use your constant, it may be needed to specify an 'l' or '​ul' Note that most compilers will issue warnings if an integer is larger than the int data type and  Therefore, we can say that data types are used to tell the variables the type of data it can store. Whenever a variable is defined in C++, the compiler allocates some memory for that variable based on the data-type with which it is declared.


If you must (for some reasons) to use automatic storage variables - increase the stack size.

for example this way:

int SeStack(rlim_t size)
{
    struct rlimit rlim;
    if(!getrlimit(RLIMIT_STACK, &rlim))
    {
        if (rlim.rlim_cur <= size)
        {
            rlim.rlim_cur = size;
            return setrlimit(RLIMIT_STACK, &rlim);
        }
        else
        {
            return 0;
        }
    }
    return EPERM;
}

An introduction to programming The Microchip PIC in CCS C, 7 Pointers Pointer Basics Pointers and Arrays Passing Pointer to Functions We will continue to use Microcontrollers like the PIC for low cost and portable In C, certain words are reserved for use by the compiler to define data types or for unsigned int 8 0 to 255 signed 8 -128 to 127 signed int 8 -128 to 127 long 16 0 to​  We are also using sizeof() operator to get size of various data types. When the above code is compiled and executed, it produces the following result which can vary from machine to machine − Size of char : 1 Size of int : 4 Size of short int : 2 Size of long int : 4 Size of float : 4 Size of double : 8 Size of wchar_t : 4 typedef Declarations


SQLite CVSTrac, For instance, "journal-10293" would be used if the starting inode for the associated Now my basic maths (a hex 16-byte aligned number should end in 0, right?) says Ordinarily I'd install software with "emerge <package>" but "​emerge sqlite" only else > typedef long long int sqlite_int64; > typedef unsigned long long int  An array is a collection of variables that are accessed with an index number. Arrays in the C++ programming language Arduino sketches are written in can be complicated, but using simple arrays is relatively straightforward. Creating (Declaring) an Array. All of the methods below are valid ways to create (declare) an array.


Device OS API, Reference manual for the C++ API used by user firmware running on Particle IoT devices. A function is limited to a single int (32-bit) return value, but you can return bool, A cloud function is set up to take one argument of the String datatype. However, if your device runs continuously for a long time, you may want to  On the other hand: It should be considered a bonus if the Keil compiler supports long int as array size - or notes that the constant 65530 is a long int but that the value still fits in a 16 bit unsigned int, and so is within the capability of the architecture.


[PDF] Solaris 64-bit Developer's Guide, des marques déposées de SPARC International, Inc. aux Etats-Unis et dans environment for building and running 64-bit applications that can use large files 64-bit arithmetic has long been available in previous 32-bit Solaris releases. After you've decided to convert your application to a full 64–bit program, it is worth. The difference between long long and int int is that long modifies a type, rather than being a type itself. long is really a shorthand for long int and long long a shorthand for long long int. More specifically int is a type specifier, just like char or bool. long is a type modifier. Other type modifiers are unsigned and signed and short.