C Compilation Example

main(char *argv[])
        int a, b, c;

        a = b;
        printf("%g\n", a);
Plain compile:
$ gcc t.c
Compile with warnings:
$ gcc -O4 -Wall -Werror t.c
cc1: warnings being treated as errors
t.c:9: warning: return-type defaults to `int'
t.c:9: warning: first argument of `main' should be `int'
t.c:9: warning: `main' takes only zero or two arguments
t.c: In function `main':
t.c:13: warning: implicit declaration of function `printf'
t.c:13: warning: double format, different type arg (arg 2)
t.c:10: warning: unused variable `c'
t.c:14: warning: control reaches end of non-void function
t.c:10: warning: `b' might be used uninitialized in this function