Question

Now I use the follow code to init buf[], but I wanna pass a string to buf[], then how can I convert string to buf[]? Thanks!

UInt8 buf[] = "hello world";

Answer 1

I’ll assume that, by “string”, you meant an NSString *.

The length of a string is unknown at compile-time, so you can’t define a UInt8 buf[] to contain the value. You have to either pre-specify the length (e.g., UInt8 buf[100]), or copy the string into heap memory and refer to it with a UInt8 *buf.

For the first approach:

UInt8 buf[100];
strncpy(buf, str.UTF8String, sizeof(buf));

For the second, this is one way to do it:

UInt8 *buf = strdup(str.UTF8String);
// Don't forget to call free(buf) later.