Error running STRLWR function under Linux: LD returned 1 exit status

Run the STRLWR function times wrong, the source program is as follows:

#include <stdio.h> #include <string.h>void main () {char s[10]={"China"}; printf ("%s\n", STRLWR (s)); return 0 ;}

The error content is as follows:

eg6527a.c:in function ' main ':

Eg6527a.c:8:2:warning: ' Return ' with a value, in function returning void [enabled by default] return 0; ^in file included from Eg6527a.c:3:0:eg6527a.c:at top level:/usr/include/strlwr.h:1:14:warning: ' strlwr ' used but never              defined [enabled by default] static char *strlwr (char *s); ^/tmp/cc6lxd8t.o:in function ' main ': eg6527a.c: (. text+0x79): Undefined reference to ' STRLWR ' Collect2:error:ld returned 1 exit status

Look for the reason, originally is the compatibility problem strlwr, the STRUPR function is not the standard C function library, can only use in the VC,

You need to define these functions yourself under Linux gcc.

The following are the specific practices:

Write yourself a strlwr.h header file that reads as follows:

Char *strlwr (char *s) {char *str; str = s; while (*str! = ') {  if (*str >= ' A ' && *str <= ' Z ') {     *s TR + = ' A '-' a '; } str++; } return s; }

Save it in the/usr/include directory

Then modify the source file to:

#include <stdio.h> #include <string.h> #include <strlwr.h>void main () {char s[10]={"China"}; printf (" %s\n ", STRLWR (s)); return 0;}

Run the program again at this time Gcc-o 6527a 6527a.c

Generate executable file 6527a

Run the file./6527a

The result is: China

Convert the string "China" to: "China"

Error running STRLWR function under Linux: LD returned 1 exit status