Question

when I end my program, I found ‘glibc detected’ message like this.
However, I do not know this is error or warning or else.. could someone explain what this message meaning and how I have to do?

Answer 1

It means you have heap corruption in your program. You likely allocate some memory using malloc, but write outside the actual bounds, corrupting the heap. When you call free, glibc detects the corruption and reports it (specifically, the size of the next free chunk is overwritten).

You should definitely fix this problem. Valgrind can be a huge help in tracking down the code that actually causes the heap corruption.