sprintf_s and access violation

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I've been getting "0xC0000005: Access violation reading location errors" in Visual Studio on Windows with a C/C++ program and have attempted to simplify to illustrate my question. The code below runs just fine:

char tmp[1000];
ULONG64 val1 = 1;
sprintf_s(tmp, 1000, "%lu, %s, %s", val1, "true", "false");

However, when I add an extra unsigned long to the format, I get an access violation, like with the code below:

char tmp[1000];
ULONG64 val1 = 1;
ULONG64 val2 = 2;
sprintf_s(tmp, 1000, "%lu, %lu, %s, %s", val1, val2, "true", "false");

acess violation when using sprintf_s in c - MSDN, I set first_octet = 11 and sure enough, i got access violation at memory location 0x000000B. Why is sprintf_s trying to read the value of the� I'm having a bit of trouble with sprintf_s(). I keep getting a currupted format into my buffer when I use it and an Access Violation. I assume I'm using it incorrectly. I'm making a function that checks the values of variables throughout my code and then tells me if there is a bug and where it occured.

The format specifier %lu is for unsigned long which is 32 bits not 64 on MSVC.

So the stacked arguments are misalinged, and MSVC should warn about this.

You could hedge with %llu but ideally use the proper format to guarantee a match for a fixed width variable.

If the type were uint64_t then for example when using printf you should have

printf("%" PRIu64 "\n", val1);

for example.

[Solved] Access Violation, Accept Solution Reject Solution. Check the size of "Buffer" - is there enough room ? Shouldn't you be providing the buffer size in your sprintf_s� The printf(), fprintf(), sprintf(), and asprintf()functions each return a negative value if an output error was encountered. The printf_s()and fprintf_s()functions each return a negative value if an output error, encoding error, or runtime constraint violation was encountered.

You mentioned in a comment that you'd prefer to use C++ where possible. Then do it, and eschew all that type-unsafe C!

#include <sstream>
#include <string>

int main()
{
    unsigned long val1 = 1;
    unsigned long val2 = 2;
    std::ostringstream sstr;

    // the true/false being a bit nonsensical, but to
    // stay close to your original code
    sstr << val1 << ", " << val2 << ", " << "true" << ", " << "false";

    std::string tmp{ sstr.str() };
}

printf, fprintf, sprintf, snprintf, printf_s, fprintf_s, sprintf_s, snprintf_s , NULL is simply another name for "0", so if you get the error "Access violation reading location 0" that means your program has told the computer� Unhandled exception at 0x00412fd0 in hybrid-rendering.exe: 0xC0000005: Access violation reading location 0x00000000. [/bquote] I know that it's pretty unsafe when using sprintf as we don't know the size of data in advance. So is there any alternative ways to do that sort of things? if someone knows how to fix this, please share with me, I will

sprintf and sprintf_s - For Beginners, printf , fprintf , sprintf , snprintf , asprintf - print formatted output printf_s the function would need to access a wide-character one past the end of the array. encoding error, or runtime constraint violation was encountered. If you get an access violation on a line of code that dereferences multiple pointers, it can be difficult to find out which pointer caused the access violation. Starting in Visual Studio 2015 Update 1, the exception dialog box now explicitly names the pointer that caused the access violation.

sprintf_s, Hey there, I'm having a bit of trouble with sprintf_s(). I keep getting a currupted format into my buffer when I use it and an Access Violation. File access: fopen fopen_s (C11) freopen freopen_s (C11) sprintf_s, and snprintf_s are or a negative value if a runtime constraints violation or an encoding

sprintf_s correct usage - C++ Forum, I got this error. Exception thrown at 0x53380B5C (ucrtbased.dll) in ConsoleApplication1.exe: 0xC0000005: Access violation writing location� One main difference between sprintf_s and sprintf is that sprintf_s checks the format string for valid formatting characters, whereas sprintf only checks if the format string or buffer are NULL pointers. If either check fails, the invalid parameter handler is invoked, as described in Parameter Validation.

Comments
  • "with a C/C++ program" There's no such language as "C/C++". It's either C, or C++. Which are you, actually, using? Once you have the answer to this question: remove the tag of the language, that you are not using.
  • Minor tidbit not weighing into the problem, but it's really wise to derive the size of a buffer from the variable itself rather than repeat the number: sprintf_s(tmp, sizeof tmp, ...). This avoids unhappy surprises if you change one and forget to change the other.
  • The program uses Windows C libraries but I try to use C++ whereever possible, like std::string
  • @publicwireless So, C++ then.
  • @WeatherVane That's not a note, it's an answer!