Compilare: user.cpp: In function ‘void huge_sum(char*, char*, char*, int, int)’: user.cpp:10:31: warning: ‘sizeof’ on array function parameter ‘c’ will return size of ‘char*’ [-Wsizeof-array-argument] memset(c , NULL , sizeof(c)); ^ user.cpp:7:44: note: declared here void huge_sum(char a[] , char b[] , char c[] , int n , int m) ^ user.cpp:10:29: warning: argument to ‘sizeof’ in ‘void* memset(void*, int, size_t)’ call is the same expression as the destination; did you mean to provide an explicit length? [-Wsizeof-pointer-memaccess] memset(c , NULL , sizeof(c)); ^ user.cpp:10:32: warning: passing NULL to non-pointer argument 2 of ‘void* memset(void*, int, size_t)’ [-Wconversion-null] memset(c , NULL , sizeof(c)); ^ user.cpp: In function ‘long long int huge_imp(char*, char*, long long int&, long long int, int)’: user.cpp:36:31: warning: ‘sizeof’ on array function parameter ‘c’ will return size of ‘char*’ [-Wsizeof-array-argument] memset(c , NULL , sizeof(c)); ^ user.cpp:34:38: note: declared here long long huge_imp(char a[] , char c[] , long long &r , long long k , int n) ^ user.cpp:36:29: warning: argument to ‘sizeof’ in ‘void* memset(void*, int, size_t)’ call is the same expression as the destination; did you mean to provide an explicit length? [-Wsizeof-pointer-memaccess] memset(c , NULL , sizeof(c)); ^ user.cpp:36:32: warning: passing NULL to non-pointer argument 2 of ‘void* memset(void*, int, size_t)’ [-Wconversion-null] memset(c , NULL , sizeof(c)); ^ user.cpp: In function ‘int main()’: user.cpp:57:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(a + 1); ^~~~ In file included from /usr/include/c++/6/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^~~~ user.cpp:57:15: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(a + 1); ^ In file included from /usr/include/c++/6/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^~~~ user.cpp:68:36: warning: passing NULL to non-pointer argument 2 of ‘void* memset(void*, int, size_t)’ [-Wconversion-null] memset(b , NULL , sizeof(b)); ^ user.cpp:55:9: warning: unused variable ‘i’ [-Wunused-variable] int i , n , m; ^ user.cpp:53:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]