/in/ex1.c: In function 'main':
/in/ex1.c:24:20: error: conversion to 'char' from 'int' may alter its value [-Werror=conversion]
             c[i] = (int)c[i] - 'A'+'a';
                    ^
/in/ex1.c:43:17: error: 'b' undeclared (first use in this function)
                 b[k]=a[j];
                 ^
/in/ex1.c:43:17: note: each undeclared identifier is reported only once for each function it appears in
cc1: all warnings being treated as errors