#define _STDC_WANT_LIB_EXT1_1
#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#define capacity 50
int main(void)
{
    char *p = (char*)malloc(capacity);
    char delimiters[] = " \" ,;:)( ";
    char **temp = NULL;
    char **buf = NULL;
    char *pstr = NULL;
    char *ptr = NULL;
    int num = 0;
    int add = 0;
    int flag = 0;

    printf("请输入一串字符:\n");
    fgets(p, capacity, stdin);
    do{
        if (num == add)
        {
            add += 3;
            temp = (char**)malloc(add);
            for (int i = 0; i < add; i++)
                *(temp + i) = (char*)malloc(capacity);
            if (buf)
            {
                for (int i = 0; i < num; i++)
                    temp[i] = buf[i];
                free(buf);
            }
            buf = temp;
            free(temp);
            temp = NULL;
        }
        if (!flag)
        {
            pstr = strtok_s(p, delimiters, &ptr);
            strcpy_s(*(buf + num++), capacity, pstr);
        }
        else
            strcpy_s(*(buf + num++), capacity, pstr);
        flag = 1;
    } while ((pstr = strtok_s(NULL, delimiters, &ptr)) != NULL);
    for (int i = 0; i < num; i++)
        printf("%s", *(buf + i));
    free(buf);
    buf = NULL;

    free(p);
    p = NULL;
    return 0;
}

  char delimiters[] = " \" ,;:)( ";

这个是嘛？

代码做什么的？

你重复多次地给temp显式分配内存，多次调用malloc()函数，对同一变量多次分配内存，结果是难以预测的。你干脆一次分配完就好了。你看看add+=3;后面的代码。改进一下就好了。你编程的意图也没人能理解