Thread: swprintf misbehaving (?!?!)

This is probably something petty or I don't understand how swprintf is supposed to work.

I have the following code:

Code:

#include <stdio.h>
#include <wchar.h>
​
int main()
{
        int count = 22;
        wchar_t data[20];
​
        swprintf(data, 20, L"x%d", count);
        wprintf(L"string : %s count : %d \n", data, count);
​
        return 0;
}

I expect that printed result to be 'x22' and the count to be 4? However, I get totally different values. Anyone know where I am going wrong?

Thanks in advance!

Try to use %ls instead.

Originally Posted by john.c

Why would count magically change to 4? swprintf doesn't modify any parameters except the first. It returns the number of characters written, which would be 3 since it doesn't count the '\0'.

Yeah, sorry.

I thought the count would include the terminating '\0'.

I posted some older code. It looks like this

Code:

#include <stdio.h>
#include <stdint.h>
#include <wchar.h>
#include <string.h>


int main(int argc, char *argv[])
{
        int count = 22;
        wchar_t data[20];


        count = swprintf(data, 20, L"%1s", count);
        wprintf(L"string : %s count : %d \n", data, count);


        return 0;
}

sprintf does exactly what I want but swprintf doesn't. ^-^

Originally Posted by ghoul

sprintf does exactly what I want but swprintf doesn't. ^-^

Did you try the suggestion in #2? Since data is a wide string, you need to use the %ls format to print it out.

Originally Posted by christop

Did you try the suggestion in #2? Since data is a wide string, you need to use the %ls format to print it out.

Originally Posted by flp1969

Try to use %ls instead.

That didn't work but %S did work. Thanks for pointing me in the right direction :-)

Originally Posted by ghoul

That didn't work but %S did work. Thanks for pointing me in the right direction :-)

Ah, looks like another Microsoft extension:
Format specification syntax: printf and wprintf functions. The standard format to print a wchar_t string is "%ls", which appears to be supported even by Microsoft. Be sure you're using the letter "l", not the digit "1" in the format. As a bonus, your code will be more portable to the rest of the world (outside of Microsoft).

Originally Posted by christop

Ah, looks like another Microsoft extension:
Format specification syntax: printf and wprintf functions. The standard format to print a wchar_t string is "%ls", which appears to be supported even by Microsoft. Be sure you're using the letter "l", not the digit "1" in the format. As a bonus, your code will be more portable to the rest of the world (outside of Microsoft).

Thanks my friend. I was actually used '1s' and hence wasn't understanding how this could be the solution.