concatenating strings and snprintf in c
I'm wondering if this is the proper way to concatenate
and NUL
terminate strings including width.
#define FOO "foo"
const char *bar = "b开发者_如何转开发ar";
int n = 10;
float f = 10.2;
char *s;
int l;
l = snprintf (NULL, 0, "%-6s %-10s %4d %4f",FOO, bar, n, f);
s = malloc (l + 4); // should it be the number of formats tags?
if (s == null) return 1;
sprintf (s, "%-6s %-10s %4d %4f", FOO, bar, n, f);
Quite a few systems have a function asprintf
in their standard C libraries that does exactly what you do here: allocate and sprintf
.
You only need to add 1
to the value returned by snprintf()
, since there is only one null terminator added.
However, you do need to check for l == -1
(indicating that snprintf()
failed).
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