我因为一个指针p_return_index而停留在这个程序上。正如它所暗示的那样，它被带入每个搜索功能，并且应该被赋予索引值，其中找到搜索到的数字。如果搜索的数字不在数组中，程序运行正常，但是当我输入数组中的数字时，会出现分段错误（核心转储）错误。传递指针我必须做错事。因为它给出了索引号。我只是不知道如何解决这个问题。请注意，指针是使用NULL初始化的;我认为这可能与它有关。我显然不知道。
void show_data(int array[], int max_index, int searched_number);
/* Display the arrays contents on screen */
void search_results(char found, int *p_return_index);
/* Prints if data is found */
int ordered_seq_search(int array[], int max_index, int searched_number, int *p_return_index);
/* Ordered Sequential Search Algorithm */
int probability_search(int array[], int max_index, int searched_number, int *p_return_index);
/* Probability Search Algorithm */
int binary_search( int array[], int max_index, int searched_number, int *p_return_index);
/* Binary Search Algorithm */
/**********************************************************************/
/* Main Function */
/**********************************************************************/
int main()
{
int searched_number,
*p_return_index = NULL,
max_index = MAX_INDEX,
seq_data[DATA_SIZE],
prob_data[DATA_SIZE],
bin_data[DATA_SIZE];
char found_status;
/* Print the program heading and instructions */
printf("\n\n\n\n\n\n\n");
print_heading();
print_instructions();
/* Fill arrays with data */
fill_array(seq_data, max_index);
fill_array(prob_data, max_index);
fill_array(bin_data, max_index);
while(printf("\n\n\nEnter an integer search target (%d to quit): ",
QUIT), scanf("%d", &searched_number), searched_number != 0)
{
printf("\n");
printf("\nOrdered Sequential Search:");
show_data(seq_data, max_index, searched_number);
if(ordered_seq_search(seq_data, max_index, searched_number, p_return_index) == 1)
{
found_status = 'S';
search_results(found_status, p_return_index);
}
else
{
found_status = 'U';
search_results(found_status, p_return_index);
}
printf("\n\n");
printf("\nProbability Search:");
show_data(prob_data, max_index, searched_number);
if(probability_search(prob_data, max_index, searched_number, p_return_index) == 1)
{
found_status = 'S';
search_results(found_status, p_return_index);
}
else
{
found_status = 'U';
search_results(found_status, p_return_index);
}
printf("\n\n");
printf("\nBinary Search:");
show_data(bin_data, max_index, searched_number);
if(binary_search(bin_data, max_index, searched_number, p_return_index) == 1)
{
found_status = 'S';
search_results(found_status, p_return_index);
}
else
{
found_status = 'U';
search_results(found_status, p_return_index);
}
}
printf("\nThanks for searching. Have a nice day! ;-)");
printf("\n\n\n\n\n");
return 0;
}
/**********************************************************************/
/* Print the program heading */
/**********************************************************************/
void print_heading()
{
printf("\n========================================================");
printf("\n Program Number: %d", PROGRAM_NUMBER);
printf("\n Programmer: %s", PROGRAMMER_NAME);
printf("\n PCC Course Number: %s", COURSE_NUMBER);
printf("\n========================================================");
return;
}
/**********************************************************************/
/* Print the program instructions */
/**********************************************************************/
void print_instructions()
{
printf("\nThis program demonstrates various search algorithms.");
printf("\nYou enter in any whole number, and the program will");
printf("\nsearch for it in an ORDERED array of whole numbers");
printf("\nusing each of the following search algorithms:");
printf("\n 1. Ordered Sequential Search");
printf("\n 2. Probability Search");
printf("\n 3. Binary Search");
printf("\nThe progress of each search is shown so the efficiency");
printf("\nof the search algorithms can be compared.");
return;
}
/**********************************************************************/
/* Fill the array */
/**********************************************************************/
void fill_array(int array[], int max_index)
{
int index_value;
for(index_value = 0; index_value <= max_index; index_value++)
array[index_value] = (index_value * 5) + 10;
return;
}
/**********************************************************************/
/* Show the data */
/**********************************************************************/
void show_data(int array[], int max_index, int searched_number)
{
int count;
printf("\n Array Index: ");
for (count = 0; count <= MAX_INDEX ; count++)
printf("[%2d]", count);
printf("\n Array Data: ");
for (count = 0; count <= MAX_INDEX; count++)
printf(" %2d ", array[count]);
printf("\n User Target: %2d", searched_number);
return;
}
/*****************************************************************/
/* Found Stuff */
/************/
void search_results(char found, int *p_return_index)
{
printf("\nSearch Outcome: ");
if(found == 'S')
printf("Successful - target found at index [%2d]", *p_return_index);
//The run-time error happens here. So, it definitely has to be the pointer.
if(found == 'U')
printf("Unsuccessful - target not found");
if(found != 'S' && found != 'U')
printf("Undetermined");
return;
}
/**********************************************************************/
/* Ordered Sequential Search */
/**********************************************************************/
int ordered_seq_search(int array[], int max_index, int searched_number, int *p_return_index)
{
int index = 0;
printf("\n Search Path: ");
while (printf("[%2d]", index),
index < max_index && searched_number != array[index - 1] &&
searched_number > array[index])
{
index++;
}
if(searched_number == array[index])
{
p_return_index = &index;
printf("\n%d", *p_return_index);
//This is just to show that `p_return_index` does get the right value.
return 1;
}
else
return 0;
}
/**********************************************************************/
/* Probability Search */
/**********************************************************************/
int probability_search(int array[], int max_index, int searched_number, int *p_return_index)
{
int index = 0;
int temp;
printf("\n Search Path: ");
while (printf("[%2d]", index),
index < max_index && searched_number != array[index])
{
index++;
}
if(searched_number == array[index])
{
p_return_index = &index;
if(index > 1)
{
temp = array[index - 1];
array[index - 1] = array[index];
array[index] = temp;
array = array - 1;
}
return 1;
}
else{
return 0;
}
}
/**********************************************************************/
/* Binary Search */
/**********************************************************************/
int binary_search( int array[], int max_index, int searched_number, int *p_return_index)
{
int begin, end, middle;
begin = 0;
end = max_index;
printf("\n Search Path: ");
while( begin <= end )
{
middle = (begin + end) / 2;
if(searched_number > array[middle])
{
printf("[%2d]", middle);
begin = middle + 1;
}
else if(searched_number < array[middle])
{
printf("[%2d]", middle);
end = middle - 1;
}
else
{
printf("[%2d]", middle);
begin = end + 1;
}
}
if(searched_number == array[middle])
{
p_return_index = &middle;
return 1;
}
else
return 0;
}
非常感谢帮助。
答案 0 :(得分：2)
你在做的是：
您声明一个指针并为其指定NULL。
将此NULL值传递给函数。
该函数尝试读取指针后面的内存。由于指针仍然存储地址NULL，因此该函数尝试读取地址为NULL的内存，该内存不存在。
将指针参数用作返回值的惯用法是：
您可以按照自己的方式定义指针参数。
void foo(int* myReturnArgument);
在调用代码中，您定义一个不是指针的变量。然后你获取该变量的地址并将其传递给函数。
int bar;
foo(&bar);
在函数中，您可以操纵指针指向的值。
void foo(int* myReturnArgument) {
*myReturnArgument = 42;
}