Zilog Z8F0130 - Manual (Page 500)

Appendix B. C Standard Library UM013037-1212
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char *array[MAXARGS];

int ptr_no = 0;

if (n_ptrs > MAXARGS)
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n_ptrs = MAXARGS;
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va_start(ap, n_ptrs);
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while (ptr_no < n_ptrs)
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array[ptr_no++] = va_arg(ap, char *);
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va_end(ap);
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f2(n_ptrs, array);

}
Each call to f1 has in scope the definition of the function of a declaration such as void
f1(int, ...);
va_start
Is executed before any access to the unnamed arguments.
The parameter ap points to an object that has type va_list . The parameter parmN is the
identifier of the rightmost parameter in the variable parameter list in the function defini-
tion (the one just before the , ...). The
va_start macro initializes ap for subsequent use
by va_arg and va_end .
Synopsis
#include

void va_start(va_list ap, parmN);
Example
The function f1 gathers into an array a list of arguments that are pointers to strings (but not
more than MAXARGS arguments), then passes the array as a single argument to function
f2. The number of pointers is specified by the first argument to f1.
#include

extern void f2(int n, char *array[]);
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#define MAXARGS 31

void f1(int n_ptrs,...) {

va_list ap;

char *array[MAXARGS];

int ptr_no = 0;

if (n_ptrs > MAXARGS)

n_ptrs = MAXARGS;

va_start(ap, n_ptrs);

while (ptr_no < n_ptrs)

array[ptr_no++] = va_arg(ap, char *);

va_end(ap);

f2(n_ptrs, array);

}