Ошибка variable sized object may not be initialized

error: variable-sized object may not be initialized

Have you ever come across this error?? 

«Understand the error thoroughly, so that it is not required to google in the future» — That’s what I say to myself.

#include <stdio.h>
#include <string.h>

int main()
{   
    int n = 15;
    char arr[n] = "Stunning Palace";
    printf("Arr [%s] and sizeof(arr) [%d] strlen(arr) [%d]n", arr, 
            sizeof(arr), strlen(arr));
    
    return 0;
}
Output:








In function 'main':
Line 7: error: variable-sized object may not be initialized







This error says,

1. Initialization has a problem.

2. Variable-length array has a problem.
The reason for the above error is we initialized the variable-length array which is not recommended.
char ARR_SIZE  = 15;

char arr[ARR_SIZE];

char arr[ARR_SIZE] = {};  //error

char arr[ARR_SIZE] = {0}; //error



  


                       
  




An array size can’t be assigned by another initializer (n = 15), but if the size is assigned by an initializer, it becomes a variable-length array. These variable-length arrays are prohibited from being initialized.
#include <stdio.h>
#include <string.h>

int main()
{   
    char ARR_SIZE  = 15;
    char arr[ARR_SIZE] = {};
    
    printf("Arr [%s] and sizeof(arr) [%d] strlen(arr) [%d]n", arr, 
            sizeof(arr), strlen(arr));
    
    return 0;
}
Output:








In function 'main':
Line 7: error: variable-sized object may not be initialized






#include <stdio.h>
#include <string.h>

int main()
{   
    char ARR_SIZE  = 15;
    char arr[ARR_SIZE] = {0};
    
    printf("Arr [%s] and sizeof(arr) [%d] strlen(arr) [%d]n", arr, 
            sizeof(arr), strlen(arr));
    
    return 0;
}
Output:








In function 'main':
Line 7: error: variable-sized object may not be initialized
Line 7: warning: excess elements in array initializer
Line 7: warning: (near initialization for 'arr')






The type of entity to be initialized shall be an array of unknown size or an object type that is not a variable-length array type, so the problem is with initialization. 
This issue can be solved by two-ways.
1. The type of entity to be initialized shall be an object type that is not a variable-length array type.
#include <stdio.h>

int main()
{   
    int n = 15;
    char arr[n];

    sprintf(arr, "Stunning Palace");
    printf("Arr [%s] and sizeof(arr) [%d] strlen(arr) [%d]n", arr, 
            sizeof(arr), strlen(arr));
    
    return 0;
}
Output:








Arr [Stunning Palace] and sizeof(arr) [15] strlen(arr) [15]






Another way of assigning array size is,
#include <stdio.h>
#define ARR_SIZE 15

int main()
{   
    char arr[ARR_SIZE] = "Stunning Palace";
    printf("Arr [%s] and sizeof(arr) [%d] strlen(arr) [%d]n", arr, 
            sizeof(arr), strlen(arr));
    
    return 0;
}
Output:








Arr [Stunning Palace] and sizeof(arr) [15] strlen(arr) [15]







2. The type of entity to be initialized shall be an array of unknown size.



  


                       
  




#include <stdio.h>
#include <string.h>

int main()
{
   char arr[] = "Stunning Palace";

    printf("Arr %s and sizeof(arr) %d strlen(arr) %dn", arr, sizeof(arr), strlen(arr));
    
    return 0;
}
Output:








Arr Stunning Palace and sizeof(arr) 16 strlen(arr) 15







Hence, the problem is with initialization with variable-length and not a declaration.
This problem is applicable to integer arrays as well.
#include <stdio.h>

int main()
{
    int n = 6;
    int arr[n] = {1, 2, 3, 4, 5, 6};

    printf("Array before memset() arr %d and sizeof(arr) %d n", arr[5], sizeof(arr));
    
    return 0;
}
Output:








In function 'main':
Line 6: error: variable-sized object may not be initialized
Line 6: warning: excess elements in array initializer
Line 6: warning: (near initialization for 'arr')
Line 6: warning: excess elements in array initializer
Line 6: warning: (near initialization for 'arr')
Line 6: warning: excess elements in array initializer
Line 6: warning: (near initialization for 'arr')
Line 6: warning: excess elements in array initializer
Line 6: warning: (near initialization for 'arr')
Line 6: warning: excess elements in array initializer
Line 6: warning: (near initialization for 'arr')
Line 6: warning: excess elements in array initializer
Line 6: warning: (near initialization for 'arr')







Integer array initialization also can be solved by the above two methods.

Today we will discuss the ERROR: variable-sized objects may not be initialized in C++. This error message typically appears in C++ when you are trying to initialize a variable-sized object, such as an array, with a non-constant expression. In C++, the size of an array must be a constant expression, so you cannot use a variable or a function call to determine the size of an array. Instead, you should use a constant or a constant expression to specify the size of the array.k.

#include 
int main()
{
        int n = 5;
        int arr[n];
        return 0;
}

#include 
int main()
{
        int size;
        std::cin >> size;
        int arr[size]; // This will give the error
        return 0;
}

#include 
int main()
{
        const int size = 5;
        int arr[size];
        return 0;
}

#include 
int main()
{
        int size;
        std::cin >> size;
        int* arr = new int[size];
        return 0;
}

#include 
int main()
{
        int size;
        std::cin >> size;
        std::vector<<span class="hljs-type">int> arr(size);
        return 0;
}