什么是细分错误？

#1 楼

int *p = NULL;
*p = 1;

char *str = "Foo"; // Compiler marks the constant string as read-only
*str = 'b'; // Which means this is illegal and results in a segfault

char *p = NULL;
{
    char c;
    p = &c;
}
// Now p is dangling

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int *arr = new int[20];
delete arr;
cout<<arr[1];  //dangling problem occurs here

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 /* "Array out of bounds" error 
   valid indices for array foo
   are 0, 1, ... 999 */
   int foo[1000];
   for (int i = 0; i <= 1000 ; i++) 
   foo[i] = i;

it arise primarily due to errors in use of pointers for virtual memory addressing, particularly illegal access.

De-referencing NULL pointers – this is special-cased by memory management hardware.

Attempting to access a nonexistent memory address (outside process’s address space).

Attempting to access memory the program does not have rights to (such as kernel structures in process context).

Attempting to write read-only memory (such as code segment).

#13 楼

 #include<stdio.h> 
 typedef struct{
   int a;
 }myStruct;   
int main(){
  myStruct *s;
  /* few lines of code */
  s->a = 5;
  return 0;
}

#14 楼

int num;
scanf("%d", num);// must use &num instead of num

int *num; 
printf("%d",*num); //*num should be correct as num only
//Unless You can use *num but you have to point this pointer to valid memory address before accessing it.

char *str;  

//Stored in read only part of data segment
str = "GfG";      

//Problem:  trying to modify read only memory
*(str+1) = 'n';

// allocating memory to num 
int* num = malloc(8); 
*num = 100; 

// de-allocated the space allocated to num 
free(num); 

// num is already freed there for it cause segmentation fault
*num = 110; 

#15 楼

int *number = NULL;
*number = 1;

int *number = malloc(sizeof(int));
*number = 1;