Compilare: user.c: In function ‘main’: user.c:11:5: warning: implicit declaration of function ‘strlen’ [-Wimplicit-function-declaration] n = strlen(v); ^ user.c:11:9: warning: incompatible implicit declaration of built-in function ‘strlen’ [enabled by default] n = strlen(v); ^ user.c:6:18: warning: unused variable ‘ci’ [-Wunused-variable] int n, k, i, ci; ^ user.c:21:12: warning: ‘i’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (n==i) { ^