其实解决问题的方法很简单-编程知识

其实解决问题的方法很简单

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本例是一个动态数组的例子，实现数据的增加、删除、根据索引修改数值、获取数值。

dynamic_array.c

#include "dynamic_array.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>dynamic_array_t *init_dynamic_array()
{dynamic_array_t *da = malloc(sizeof(dynamic_array_t));da->items = calloc(DEFAULT_CAPACITY, sizeof(void *));da->capacity = DEFAULT_CAPACITY;return da;
}void *add(dynamic_array_t *da, const void *value)
{if (da->size >= da->capacity){void **newItems = realloc(da->items, (da->capacity <<= 1) * sizeof(void **));//free(da->items);da->items = newItems;}void *copy_value = retrive_copy_of_value(value);da->items[da->size++] = copy_value;return copy_value;
}void *put(dynamic_array_t *da, const void *value, const unsigned index)
{if (!contains(da->size, index))return INDEX_OUT_OF_BOUNDS;free(da->items[index]);void *copy_value = retrive_copy_of_value(value);da->items[index] = copy_value;return copy_value;
}void *get(dynamic_array_t *da, const unsigned index)
{if (!contains(da->size, index))return INDEX_OUT_OF_BOUNDS;return da->items[index];
}void delete (dynamic_array_t *da, const unsigned index)
{if (!contains(da->size, index))return;for (unsigned i = index; i < da->size; i++){da->items[i] = da->items[i + 1];}da->size--;free(da->items[da->size]);
}unsigned contains(const unsigned size, const unsigned index)
{//printf("size:%d,index:%d\n", size, index);if (size >= 0 && index < size)return 1;printf("index [%d] out of bounds!\n", index);return 0;
}void *retrive_copy_of_value(const void *value)
{void *value_copy = malloc(sizeof(void *));memcpy(value_copy, value, sizeof(void *));return value_copy;
}

dynamic_array.h

#ifndef __DYNAMIC_ARRAY__
#define __DYNAMIC_ARRAY__
#define DEFAULT_CAPACITY 1 << 4
#define INDEX_OUT_OF_BOUNDS NULLtypedef struct dynamic_array
{void **items;unsigned size;unsigned capacity;
} dynamic_array_t;extern dynamic_array_t *init_dynamic_array();extern void *add(dynamic_array_t *da, const void *value);extern void *put(dynamic_array_t *da, const void *value, unsigned index);extern void *get(dynamic_array_t *da, const unsigned index);extern void delete (dynamic_array_t *da, const unsigned index);unsigned contains(const unsigned size, const unsigned index);extern void *retrive_copy_of_value(const void *value);

main.c

#include "dynamic_array.h"int main()
{dynamic_array_t *da = init_dynamic_array();for (int i = 1; i <= 50; i++){add(da, &i);}delete (da, 10);int value = 999;put(da, &value, 0);#if 1//value = 666;int another_value = 666;add(da, &another_value);#endif#if 0for (int i = 0; i < da->size; i++){printf("value[%d]=%d\n",i, *(int *)get(da, i));}
#endifint value_for_invalid_index = 10000;//put(da, &value_for_invalid_index, 150);//put(da, &value_for_invalid_index, 65);put(da, &value_for_invalid_index, 49);for (int i = 0; i < da->size; i++){printf("value[%d]=%d\n",i, *(int *)get(da, i));}free(da->items);return 0;
}

Makefile:

CC = gcc
CFLAGS = -g -Wallall: mainmain: main.o dynamic_array.o$(CC) $(CFLAGS) $^ -o $@dynamic_array.o: dynamic_array.c$(CC) $(CFLAGS) -c $^clean: rm *.o main

刚开始运行结果是这样的：

于是乎这样调试：

利用core文件调试：

先设置一下

ulimit -c unlimited

运行一下在当前目录下生成core文件

root@ubuntu-virtual-machine:/home/ubuntu/test# gdb main

gdb结合core文件调试

代码修正后运行结果：

value[0]=999
value[1]=2
value[2]=3
value[3]=4
value[4]=5
value[5]=6
value[6]=7
value[7]=8
value[8]=9
value[9]=10
value[10]=12
value[11]=13
value[12]=14
value[13]=15
value[14]=16
value[15]=17
value[16]=18
value[17]=19
value[18]=20
value[19]=21
value[20]=22
value[21]=23
value[22]=24
value[23]=25
value[24]=26
value[25]=27
value[26]=28
value[27]=29
value[28]=30
value[29]=31
value[30]=32
value[31]=33
value[32]=34
value[33]=35
value[34]=36
value[35]=37
value[36]=38
value[37]=39
value[38]=40
value[39]=41
value[40]=42
value[41]=43
value[42]=44
value[43]=45
value[44]=46
value[45]=47
value[46]=48
value[47]=49
value[48]=50
value[49]=10000