C : memcpy to the "end" of a buffer-CodePudding

I got a giant buffer and I need to write strings and ints to it.

I know you can write to it using memcpy / memmove. But in that case, I'd have to offset each variable.

Example :

int a = 10;
char *s = "hello world";
char buf[100];
memcpy(buf, a, 4);
memcpy(buf   4, s, strlen(s))

As you can see I need to offset 4 to the second memcpy for it to work.

I got tons of variables. I don't want to offset each one of them. Is it possible to do so ?

PS : the buffer is exactly the size of the sum of all variables

CodePudding user response：

You can keep the current offset in a separate variable and increase it for each value you copy in.

int a = 10;
char *s = "hello world";

char buf[100];
int offset = 0;

memcpy(buf   offset, &a, sizeof(a));
offset  = sizeof(a);
memcpy(buf   offset, s, strlen(s))
offset  = strlen(s);

This also has the advantage that you can reorder fields by moving pairs of lines around without having to renumber anything.