Why is my char* writable and sometimes read only in C++

Question

I have had really big problems understand the char* lately. Let\'s say I made a recursive function to revert a char* but depending on how I initial

Answer 1

The key is that some of these pointers are pointing at allocated memory (which is read/write) and some of them are pointing at string constants. String constants are stored in a different location than the allocated memory, and can't be changed. Well most of the time. Often vulnerabilities in systems are the result of code or constants being changed, but that is another story.

In any case, the key is the use of the new keyword, this is allocating space in read/write memory and thus you can change that memory.

This statement is wrong

char * bob = new char[6];
bob = "hello\0";

because you are changing the pointer not copying the data. What you want is this:

char * bob = new char[6];
strcpy(bob,"hello");

or

strncpy(bob,"hello",6);

You don't need the nul here because a string constant "hello" will have the null placed by the compiler.