链表数组中的分段错误

Question

I'm tryin to create an array of linked lists and have run into a problem with just the array. The code runs fine(or at least printf runs in the function) but when I try to loops through in main to print I get a segmentation fault and the lines don't print in the newLabel function.

void newLabel(char *n, Label **p, int len) {
  p[len] = malloc(sizeof(Label));
  p[len]->next = NULL;
  p[len]->name = malloc(sizeof(char) * strlen(n)+1);
  strcpy(p[len]->name, n);
  printf("%s", p[len]->name);
  ++labels;
}

int main(int argc, char const *argv[]) {
  Label *p[100];
  for (labels = 0; labels < 5; labels++) {
    newLabel("Hi", p, labels);
  }

  for (int i = 0; i <= labels; i++) {
    printf("%s", p[labels]->name);
  }
  return 0;
}

Answer 1

  for (labels = 0; labels < 5; labels++) {
    newLabel("Hi", p, labels);
  }

In this loop you allocated first 5 elements of *p

  for (int i = 0; i <= labels; i++) {
    printf("%s", p[labels]->name);
  }

I this next loop you are accessing 6th member which has not been allocated

Answer 2

Check out your code

    for (int i = 0; i <= labels; i++) { //problem here 
    printf("%s", p[labels]->name);
  }

you are execute a loop start from 0 to labels(5). it means it run for labels value 0,1,2,3,4,5 ie 6 times while you are allocate memory for only 5 elements in below code

for (labels = 0; labels < 5; labels++) {
    newLabel("Hi", p, labels);
  }

solution is remove = from for loop ie for loop syntax is

for (int i = 0; i < labels; i++)

Answer 3

By the end of this loop here

for (labels = 0; labels < 5; labels++) {
    newLabel("Hi", p, labels);
  }

labels is 5 which is never initialized, yet in below loop you are still trying to print p[5]

  for (int i = 0; i <= labels; i++) {
    printf("%s", p[labels]->name); // this labels can be 5 here
  }

So loop within boundaries

for (int i = 0; i < labels; i++) {
    printf("%s", p[labels]->name);
  }