Compilare: user.cpp: In function ‘void del()’: user.cpp:10:9: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] a[i]=NULL; ^ user.cpp: In function ‘int main()’: user.cpp:28:22: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘char (*)[100005]’ [-Wformat=] scanf("%s",&a); ^ user.cpp: In function ‘void cit()’: user.cpp:19:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("charlie.in","r",stdin); ^ user.cpp:20:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("charlie.out","w",stdout); ^ user.cpp: In function ‘int main()’: user.cpp:25:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&test); ^ user.cpp:28:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",&a); ^ user.cpp:69:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("\n%c%c",&a[0],&a[1]); ^ user.cpp:72:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&c); ^ user.cpp:80:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&c); ^