Compilare: main.cpp: In function 'int main()': main.cpp:17:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for(i = 0; i <= ch.length(); ++i) | ~~^~~~~~~~~~~~~~ main.cpp:24:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 24 | while(st >= 1 && dr <= ch.length() && pal[st+1][dr-1]) | ~~~^~~~~~~~~~~~~~ main.cpp:34:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for(i = 1; i <= ch.length(); ++i) | ~~^~~~~~~~~~~~~~ main.cpp:42:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 42 | while(st >= 1 && dr <= ch.length() && pal[st+1][dr-1]) | ~~~^~~~~~~~~~~~~~ main.cpp:70:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 70 | for(i = 1; i <= ch.length(); ++i) | ~~^~~~~~~~~~~~~~ main.cpp:12:9: warning: unused variable 'n' [-Wunused-variable] 12 | int n, i, j; | ^