vararg.cpp
867 Bytes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
#include <cstdarg>
#include <iostream>
#include <sstream>
using namespace std;
extern void error(int...);
const char* Null_cp = 0;
int main(int argc, char* argv[])
{
switch (argc) {
case 1:
error(0, argv[0], Null_cp);
break;
case 2:
error(0, argv[0], argv[1], Null_cp);
break;
default:
ostringstream s;
s << argc - 1;
string ss = s.str();
error(1, argv[0], "with", ss.c_str(), "arguments", Null_cp);
}
//...
}
void error(
int severity...) // "severity" followed by a zeroterminated list of char*s
{
va_list ap;
va_start(ap, severity); // arg startup
for (;;) {
char* p = va_arg(ap, char*);
if (p == 0)
break;
cerr << p << ' ';
}
va_end(ap); // arg cleanup
cerr << '\n';
if (severity)
exit(severity);
}