Compilare: user.c: In function ‘main’: user.c:5:5: warning: implicit declaration of function ‘strlen’ [-Wimplicit-function-declaration] freopen("palindrom.in","r",stdin),freopen("palindrom.out","w",stdout),scanf("%s",s),printf("%s",s),n=strlen(s); ^ user.c:5:106: warning: incompatible implicit declaration of built-in function ‘strlen’ [enabled by default] freopen("palindrom.in","r",stdin),freopen("palindrom.out","w",stdout),scanf("%s",s),printf("%s",s),n=strlen(s); ^ user.c:5:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("palindrom.in","r",stdin),freopen("palindrom.out","w",stdout),scanf("%s",s),printf("%s",s),n=strlen(s); ^ user.c:5:46: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("palindrom.in","r",stdin),freopen("palindrom.out","w",stdout),scanf("%s",s),printf("%s",s),n=strlen(s); ^ user.c:5:80: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("palindrom.in","r",stdin),freopen("palindrom.out","w",stdout),scanf("%s",s),printf("%s",s),n=strlen(s); ^