c - Can I define an array inside a loop with its size varying every iteration

I need to define array length for each iteration to do some operation on the array elements.
But the array size varies for every iteration. Hence I defined array size as arr[totalLen]: but the totalLen varies every iteration.

• I can not use malloc since dynamic memory allocation is disallowed for the real time system I am working

1)
Is this a proper way of defining an array? Does the scope of the element "arr" (memory allocation and life of the variable) change every iteration?

Or

2) is it a preferred way to define an array before the for loop with maximum number of elements?

/* some code here - to get the task info */
while (task[i].info!= NULL) 
{
    printf("\n Task Name is %s", task[i].Name);        
    scenario1= scenario2= scenario3= scenario4= 0;
    nvStruct  = (int '*)(TablesPtr->NVData );

    /* do something when each of the following scenario occurs */

    if ((scenario1= (!strcmp(task[i].Name, "Scenario1"))) || 
        (scenario2= (!strcmp(task[i].Name, "Scenario2"))) ||
        (scenario3= (!strcmp(task[i].Name, "Scenario3"))) ||
        (scenario4= (!strcmp(task[i].Name, "Scenario4")))) 
    {
        totalLen = *(nvStruct+1); // size of the struct
        printf("\nLength of the struct is %d", totalLen);

        int32 arr[totalLen]; // is this proper usage?


        for (uint32 len = 0; len < (totalLen)/4; len++)
            arr[len] = *(nvStruct+len);

        /* do something else with the array here */
        ....
        i++;