So I'm currently working on a project which uses ncurses for output and input. In this program, the user should be able to, for example, write his name. The issue I'm having is with getnstr, as it can cause some very weird and unexplainable segmentation faults. For example this code right here works fine as it is:
#include <ncurses.h>
#include <string>
int main()
{
char *word;
initscr();
WINDOW *window = newwin(100, 100, 0, 0);
nodelay(window, false);
refresh();
mvwgetnstr(window, 0, 0, word, 10);
mvwprintw(window, 0, 0, "Word written is %s", word);
wrefresh(window);
getch();
endwin();
}
However if I only add a single string variable inside of the main function for example in the form of this:
#include <ncurses.h>
#include <string>
int main()
{
std::string crashMe;
char *word;
initscr();
WINDOW *window = newwin(100, 100, 0, 0);
nodelay(window, false);
refresh();
mvwgetnstr(window, 0, 0, word, 10);
mvwprintw(window, 0, 0, "Word written is %s", word);
wrefresh(window);
getch();
endwin();
}
It will instead have a segmentation fault on the first keypress you are doing with getnstr. I'm not sure if it's only on my computer or if I'm doing something horribly wrong with ncurses but I find it weird that initializing a string variable is causing the issue. The same issue can be reproduced by introducing an additional char* into the same brackets as the getnstr.
If anyone has any thoughts about this issue, I'd greatly appreciate hearing them. Idk if it might be a C related thing causing my segmentation faults. Either way, thanks in advance.
You're asking to read 10 characters into a pointer that points nowhere in particular. Try either char word[10]; or char *word = malloc(10);
So why does that sometimes work? Your uninitialized pointer variable may have pointed to a writable memory area by accident. You were overwriting something somewhere, which may not always immediately crash.
I'm pretty sure that should have produced a compiler warning. Always compile with -Wall and pay attention to the output.