问题
I want to sprintf() an unsigned long long value in visual C++ 6.0 (plain C).
char buf[1000]; //bad coding
unsigned __int64 l = 12345678;
char t1[6] = "test1";
char t2[6] = "test2";
sprintf(buf, "%lli, %s, %s", l, t1, t2);
gives the result
12345678, (null), test1
(watch that test2 is not printed)
and l = 123456789012345 it gives an exception handle
any suggestions?
回答1:
To print an unsigned __int64 value in Visual C++ 6.0 you should use %I64u, not %lli (refer to this page on MSDN). %lli is only supported in Visual Studio 2005 and later versions.
So, your code should be:
sprintf(buf, "%I64u, %s, %s", l, t1, t2);
回答2:
printf uses the ellipsis to pass a variable argument list. The (null) you see is the second part of your long long, which happen to be all 0 bits. Set it to 1<<60+1<<30 and you'll get a crash as the 1<<60 part is interpreted as a char*.
The correct solution would be to break down the number in three parts of 10 digits, "verylongvalue % 10000000000" "(verylongvalue/10000000000) % 10000000000" "verylongvalue/100000000000000000000".
回答3:
Apparently, you did not assign additionaltext to the necessary char * (string). Note that the long int was processed, the comma was copied and only the %s generated (null).
来源：https://stackoverflow.com/questions/200676/visualc-6-0-with-unsigned-long-long-and-sprintf