sscanf_s 在 Visual Studio 2012 中出现错误

Question

我正在尝试解析以下字符串 - "DATA,97,103,100,97,84,69"。这个字符串可以有以下变体-

"DATA,100,10,1,9,82,60"
"DATA,57,27,59,30,11,64"
"DATA,12,86,100,97,103,23"
"DATA,1,10,78,38,45,52"
"DATA,99,43,85,28,84,26"

请注意，第一个 "DATA," 永远不会改变。其余整数从0到200不等。下面是使用sscanf_s函数解析这些字符串的代码-

char ignore_data[5];
int x1,x2,x3,y1,y2,y3;
char str[]="DATA,97,103,100,97,84,69";

sscanf_s(str,"%5[^,],%d,%d,%d,%d,%d,%d", ignore_data, &x1, &x2, &x3, &y1, &y2, &y3);
printf("str=%s, x1=%d, x2=%d, x3=%d, x1=%d, y2=%d, y3=%d",str, x1, x2, x3, y1, y2,y3);

代码无效并显示以下错误

Unhandled exception at 0x510A06E4 (msvcr110d.dll) in My Application.exe: 0xC0000005: Access violation writing location 0x00870000.

当 sscanf() 与 #define _CRT_SECURE_NO_WARNINGS 预处理器一起使用时，上述代码可以完美运行。

我想获取 x1、x2、x3、y1、y2 和 y3 的值。我在这里错过了什么？

Answer 1

引用C11标准，附件K，章节§K.3.5.3.2，fscanf_s()函数，（强调我的)

The fscanf_s() function is equivalent to fscanf() except that the c, s, and [ conversion specifiers apply to a pair of arguments (unless assignment suppression is indicated by a *). The first of these arguments is the same as for fscanf(). That argument is immediately followed in the argument list by the second argument, which has type rsize_t and gives the number of elements in the array pointed to by the first argument of the pair. [...]

现在，进入 sscanf_s() 的范围，章节 §K.3.5.3.7

The sscanf_s function is equivalent to fscanf_s, except that input is obtained from a string (specified by the argument s) rather than from a stream. [...]

希望以上文字足以指出错误，您缺少格式字符串中存在的 [ 所需的第二个参数。您需要提供 ignore_data 的大小，如 rsize_t 类型。

Answer 2

我发现如果您能够执行以下操作，您应该能够获得所需的结果：

#include <stdio.h>

int main()
{
    char ignore_data[5];
    int x1, x2, x3, y1, y2, y3;
    char str[] = "DATA,97,103,100,97,84,69";

    sscanf_s(str, "%5[^,],%d,%d,%d,%d,%d,%d", ignore_data, sizeof(ignore_data), &x1, &x2, &x3, &y1, &y2, &y3);
    printf("str=%s, x1=%d, x2=%d, x3=%d, x1=%d, y2=%d, y3=%d", str, x1, x2, x3, y1, y2, y3);

    return 0;
}

对于sscanf_s，在接收字符串时，在扫描数据后您将立即需要目标缓冲区的大小。这有助于在输入流（无论它是什么）到目的地之间建立一个安全端口，减少接受字符串时缓冲区溢出的可能性。

编辑：

正如 Cremno 指出的那样，它需要 sscanf_s(str, "%5[^,],%d,%d,%d,%d,%d,%d", ignore_data, (unsigned)sizeof(ignore_data), &x1, &x2, &x3, &y1, &y2, &y3);

注意 sizeof(ignore data) 应该 return 一个无符号值。

sscanf_s 在 Visual Studio 2012 中出现错误

Getting error with sscanf_s in Visual Studio 2012

c

input

scanf

visual-studio-2012

编辑：