在c中连接字符串和snprintf
我想知道这是否是连接和NUL终止字符串（包括宽度）的正确方法。
#define FOO "foo"
const char *bar = "bar";
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);
I'm wondering if this is the proper way to concatenate and NUL terminate strings including width.
#define FOO "foo"
const char *bar = "bar";
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);
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相当多的系统在其标准 C 库中都有一个函数
asprintf，它的功能与您在这里所做的完全一样：分配和sprintf。Quite a few systems have a function
asprintfin their standard C libraries that does exactly what you do here: allocate andsprintf.您只需将
1添加到snprintf()返回的值中，因为只添加了一个空终止符。但是，您确实需要检查
l == -1（表明snprintf()失败）。You only need to add
1to the value returned bysnprintf(), since there is only one null terminator added.However, you do need to check for
l == -1(indicating thatsnprintf()failed).