everest% CC -c astring2.C
"astring2.C", line 50: error(1133): expression must be a modifiable lvalue
          length = 0 ;
          ^

"astring2.C", line 54: error(1133): expression must be a modifiable lvalue
     length = strlen(str) ;
     ^

2 errors detected in the compilation of "astring2.C".
everest%