Compilare: user.cpp: In function ‘int sum(char*, int&)’: user.cpp:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (pos < strlen(s) && s[pos] == '+') ^ user.cpp: In function ‘int main()’: user.cpp:73:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.in", "r", stdin); ^ user.cpp:74:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.out", "w", stdout); ^ user.cpp:76:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &k); ^ user.cpp:79:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf(" %d %d", &i, &j); ^ user.cpp:80:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf(" %s", a[i][j]); ^