Verify whether snprintf ends with null

Yesterday, a colleague asked me if the end of snprintf must be '\ 0'. I have seen that strncpy does not necessarily end with' \ 0. It seems inappropriate to get up early today. Just try it. The following is the result.

Test code

#include <stdio.h>int main(void){    char szBuf[10] = {0};    snprintf(szBuf, sizeof(szBuf), "1234567890");    printf(szBuf);    printf("\n");    if (szBuf[9] == '\0')    {        printf("null end\n");    }    return 0;}

Environment 1

SunOS solx55 5.10Generic _ 144489-17 i86pc i386 i86pc

Result

User % a. out

123456789

Null end

Man Manual

The snprintf () function is identical tosprintf () with

Addition of the argument n, whichspecifies the size of

Buffer referred to by s. If n is 0, nothing is written and s

Can be a nullpointer. Otherwise, output bytes beyond

N-1st are discarded instead of being written to the array

And a null byte is written at theend of the bytes actually

Written into the array.

Environment 2

User % uname-

Linux rhel65 2.6.32-131.0.15.el6.x86 _ 64 # 1SMP Tue May 10 15:42:40 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

Result

User % a. out

123456789

Null end

The Administrator does not have an installation manual, so there is no man manual.

Environment 3

User @ ibm182 ~ $ Uname-

AIX ibm182 3 5 00033CE7D600

User @ ibm182 ~ $ A. out

123456789

Null end

Man Manual

The snprintf subroutine converts, formats, and stores the Value parameter values, under control of the Format parameter, into consecutive bytes, starting at the address specified by the Stringparameter. the snprintf subroutine places a null character (\ 0)
At the end. Youmust ensure that enough storagespace is available to contain the formatted string
With the addition ofthe Number parameter, which statesthe size of the buffer referred to by the String parameter.

Environment 4

User % uname-

HP-UX hp12162 B .11.31 U ia64 0887221123 unlimited User License

Result

User % a. out

123456789

Null end

Man Manual

Snprintf () behaves like sprintf (), effectthat it limits the number

Characters written to the destination buffer to maxsize, including

Terminating null character.

Obviously, all four environments end with '\ 0', and Windows platforms will not be tested.