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If it is necessary for p to be defined with file scope, but str with a more limited scope, then p can be set to NULL before str is destroyed. This practice prevents p from taking on an indeterminate value, although any references to p must check for NULL.

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In this noncompliant code sample, the function init_array() returns a pointer to a local stack variable, which could be accessed by the caller.:

char *init_array(void) {
   char array[10];
   /* Initialize array */
   return array;
}

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The solution, in this case, depends on the intent of the programmer. If the intent is to modify the value of array and have that modification persist outside of the scope of init_array(), the desired behavior can be achieved by declaring array elsewhere and passing it as an argument to init_array().:

void init_array(char array[]) {
   /* Initialize array */
   return;
}

int main(int argc, char *argv[]) {
   char array[10];
   init_array(array);
   /* ... */
   return 0;
}

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The variable local does not go out of scope for the entire program so, ptr is live and valid in the function rodent().:

char local[10];
 
void squirrel_away(char **ptr_param) {
    /* Initialize array */
   *ptr_param = local;
}

void rodent() {
  char *ptr;
  squirrel_away(&ptr);
  /* ptr is live and valid here */
}

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Bibliography

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