Bell 32V development

[unix-history] / usr / lib / learn / C / L31.1a

#print
Write a function named "rev(s)" which reverses
the string "s" in place. Name the file that contains
the function "rev.c".
When you're satisfied, type "ready".
#once #create Ref
cbax0987654321
#once #create tzaqc.c
main(){
       char *s1, *s2, *s3, *s4;
       s1 = "abc";
       s2 = "x";
       s3 = "";
       s4 = "1234567890";
       rev(s1);
       rev(s2);
       rev(s3);
       rev(s4);
       printf(s1);
       printf(s2);
       printf(s3);
       printf(s4);
       printf("\n");
}
#user
cc tzaqc.c rev.o
a.out >value
#cmp value Ref
#succeed
One way:

rev (s)
char *s;
{
       char *p;
       int t;
       
       for (p=s; *p; p++)
               ;
       for (p--; p > s; p--, s++) {
               t = *p;
               *p = *s;
               *s = t;
       }
}
#log
#next
32.1a 10