Operation sequence data table structures

It relates to the sequence table + deletions expansion (which say nothing directly look at the code)

/*************************************************************************
	> File Name: 1.cpp
	> Author: 
	> Mail: 
	> Created Time: 2020年02月12日 星期三 10时35分04秒
 ************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

typedef struct vector{
    int *data;
    int size, length;
}Vector;

Vector *init(int n){
    Vector *vec = (Vector *)malloc(sizeof(Vector));
    vec->data = (int *)malloc(sizeof(int) * n);
    vec->size = n;
    vec->length = 0;
    return vec;
}

void clear(Vector *vec){
    if(vec == NULL) return ;
    free(vec->data);
    free(vec);
    return ;
}

int expand(Vector *vec){
    int extra_size = vec->size;
    int *p;
    while(extra_size){
        p = (int *)realloc(vec->data, sizeof(int) * (extra_size + vec->size));
        if(p) break;
        extra_size /= 2;
    }
    if(p == NULL) return 0;
    vec->data = p;
    vec->size += extra_size;
    return 1;
}

int insert(Vector *vec, int loc, int val){
    if(vec == NULL) return 0;
    if(loc < 0 || loc > vec->length) return 0;
    if(vec->length == vec->size){
        if(!expand(vec)) return 0;
        printf("expand successfully ! size = %d\n", vec->size);
    }
    for(int i = vec->length; i > loc; i--){
        vec->data[i] = vec->data[i - 1];
    }
    vec->data[loc] = val;
    vec->length++;
    return 1;
}

int erase(Vector *vec, int loc){
    if(vec == NULL) return 0;
    if(loc < 0 || loc >= vec->length) return 0;
    for(int i = loc + 1; i < vec->length; i++){
        vec->data[i - 1] = vec->data[i];
    }
    vec->length--;
    return 1;
}

void output(Vector *vec){
    printf("Vector(%d) = [", vec->length);
    for(int i = 0; i < vec->length; i++){
        i && printf(", ");
        printf("%d", vec->data[i]);
    }
    printf("]\n");
    return ;
}

int main(){
    srand(time(0));
    #define max_op 20
    Vector *vec = init(1);
    int op, loc, val;
    for(int i = 0; i < max_op; i++){
        op = rand() % 4;
        loc = rand() % (vec->length + 3) - 1;
        val = rand() % 100;
        switch(op) {
            case 0:
            case 1:
            case 2: {
                printf("insert %d at %d to Vector = %d\n", val, loc, insert(vec, loc, val));
            }break;
            case 3: {
                printf("erase item at %d from Vector = %d\n", loc, erase(vec, loc));
            }break;
        }
        output(vec);
        printf("\n");
    }
    clear(vec);
    return 0;
}