Variable changed after function gets called again in C - c

Question

I created a struct and a function that returns that struct.
Afterwards I'm calling that function twice, each time assigned to a different variable.
The problem is that the first variable changes after the second run.
What am I missing here?
code:
struct text_and_len {
char* text;
int len;
};
struct text_and_len get_text_and_length(){
int len;
scanf("%d ", &len);
char text[len];
fgets(text, len+1, stdin);
return (struct text_and_len) {text, len};
}
void get_input_and_check_is_within(){
struct text_and_len b = get_text_and_length();
printf("%s \n", b.text);
struct text_and_len a = get_text_and_length();
printf("%s \n", a.text);
printf("%s \n", b.text);
this will first print the b.text, but then will print the a.text twice.

Answer 1

These lines used in get_text_and_length()():
char text[len];
fgets(text, len+1, stdin);//over writes buffer by at least 1, 2 if wanting a C string. Will cause undefined behavior.(UB)
will potentially allow user to enter input that would over write the buffer.
The code as is also includes variables that reach end of life before they are needed else where, resulting in predictable, but unwanted behavior.
Also the member in the struct char* text; requires memory be allocated before being written to. Thus will also require freeing.
Below is your code refactored to address these, with some other modifications to the prototypes and calling methods that simplify the writing of the code...
struct text_and_len {
char* text;
int len;
};
void get_text_and_length(struct text_and_len *b){
printf("Enter max length of input string\n");
scanf("%d ", &(b->len));
//b->text[b->len];//VLA, but has already been declared as char *
b->text = malloc(b->len + 2);//room for NULL terminator AND newline
memset(b->text, 0, b->len+2);//zero variable to all NULL
//fgets(text, len+1, stdin);//text has no memory
//and as is would have over-written
//buffer - UB
printf("Enter string no longer than max length\n");
fgets(b->text, b->len+2, stdin);//note len+2 provides room
//for len char + NULL + newline
}
void get_input_and_check_is_within(struct text_and_len *b){
get_text_and_length(b);
printf("max length: %d \n", b->len);
printf("text entered:%s \n", b->text);
}
int main(void)
{
struct text_and_len a = {0};
get_input_and_check_is_within(&a);
free(a.text);//allocated in get_text_and_length()
return 0;
}