Thread: Strings in C

Originally Posted by RyanC

Another question about increasing const pointer.
If I do char str[20]="hello" ; then I cant increase str++ for printing every char in the array ye? Because str is a const pointer...am I right?

In this case, str is an array, not a pointer. You can't change the "value" of an array like you can with a pointer.

A string, in C is an array of chars where the last char is '\0' (NUL char)... Because it is an array, a pointer points to the first element of this array, so the pointer isn't "the string", but a reference to it.

When you declare an array with fixed size, it's name is a const pointer to the first element (cannot be changed), unless when used in a function argument. In this later case, the array notation is only a sintatic helper, since the argument is, indeed, a pointer:

Code:

int f(int buff[30]); // this...
int f(int *buff); // ... is the same as this

No array bounds are checked.

Of course you can make a pointer constant using 'const' keyword:

Code:

int f( int * const buff ); // buff cannot be changed inside the function, but the pointed data can.
int f( const int *buff ); // buff can be changed inside the function, but the pointed data can't.
int f( const int * const buff ); // neither buff or pointed data can be changed.

Originally Posted by flp1969

A string, in C is an array of chars where the last char is '\0' (NUL char)... Because it is an array, a pointer points to the first element of this array, so the pointer isn't "the string", but a reference to it.

When you declare an array with fixed size, it's name is a const pointer to the first element (cannot be changed), unless when used in a function argument. In this later case, the array notation is only a sintatic helper, since the argument is, indeed, a pointer:

Code:

int f(int buff[30]); // this...
int f(int *buff); // ... is the same as this

No array bounds are checked.

Of course you can make a pointer constant using 'const' keyword:

Code:

int f( int * const buff ); // buff cannot be changed inside the function, but the pointed data can.
int f( const int *buff ); // buff can be changed inside the function, but the pointed data can't.
int f( const int * const buff ); // neither buff or pointed data can be changed.

So if I have declared char str[20]="hello" ; and I want to incrase the pointer of the array; can I do this str++? Or it's constant and cant change and do str++?