int main()
{
char *x = "HelloWorld";
char y[] = "HelloWorld";
x[0] = 'Z';
//y[0] = 'M';
return 0;
}
In the above program, HelloWorld
will be in read-only section(i.e string table). x
will be pointing to that read-only section, so trying to modify that values will be undefined behavior.
But y
will be allocated in stack and HelloWorld
will be copied to that memory. so modifying y will works fine. String literals: pointer vs. char array
Here is my Question:
In the following program, both char *arr
and char arr[]
causes segmentation fault if the content is modified.
void function(char arr[])
//void function(char *arr)
{
arr[0] = 'X';
}
int main()
{
function("MyString");
return 0;
}
Please share your knowledge.
Inside the function parameter list, char arr[]
is absolutely equivalent to char *arr
, so the pair of definitions and the pair of declarations are equivalent.
void function(char arr[]) { ... }
void function(char *arr) { ... }
void function(char arr[]);
void function(char *arr);
The issue is the calling context. You provided a string literal to the function; string literals may not be modified; your function attempted to modify the string literal it was given; your program invoked undefined behaviour and crashed. All completely kosher.
Treat string literals as if they were static const char literal[] = "string literal";
and do not attempt to modify them.