VA_LIST on 64-bit

[saurabhchokshi]

Hello all,

I am using vfprintf in my application. I am using va_list as a char * and then typecast it with va_list data type.

This thing works on 32-Bit platform. However, it doesn't work on 64-Bit platform.

Do va_start, va_copy and va_stop will solve this issue?

For Example, This is the existing code on 32-bit

char t[5];
char *p_t;

p_t = t;

while(){
vfprintf(fd, p_format , p_t + sizeof(void *))
}

However, I want to execute the same code with va_start, va_copy and va_end between vfprintf. Will this work?

I have tried but didn't get it through. Could you please help me out to resolve this issue?

Thanks,
Saurabh

[Banfa]

If you use the proper macros then it should work. The problem with what you have done is because the the difference in pointer size between 32 and 64 systems.

[saurabhchokshi]

What kind of macro I should use to run this code? Do I need to use va_start, va_copy and va_end macros?

The same code executes on 32 bit platform. I have noticed one more thing on 64-bit platform, size of va_list = 24 bytes on 64 bit and 4 bytes on 32 bit.

Any clue how to use the vfprintf in this scenario?