情况
我试图实现一个更有趣的归并排序,它创建一个具有随机值的随机长度数组,然后将它们随机化,但在调试和编译后它出现了段错误。我不知道它为什么会出现段错误,但我确定它与内存分配有关。
问题
为什么这段代码会导致段错误?
代码
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// Declare some stuff up front
int array_size(int *array);
int print_array(int *array);
//Some decade old main function coming at you
int main() {
//Concerned with the integrity of my rand
srand( (unsigned)time( NULL ));
//A global, random length array between 1 and 100?
int *array;
array = malloc(sizeof(*array) * ((rand() % 100) + 1));
init_array(*array);
getchar();
return 0;
}
int init_array(int *array) {
//Base case
array[0] = 1;
//random values for i in array
int i;
for(i = 1; i <= array_size(array); i++) {
array[i] = rand() % array_size(array) + 1;
}
//randomize the random values in the random length array
for (i = 0; i < (array_size(array) - 1); i++)
{
unsigned int swapA = (rand() % array_size(array)) + 1;
int a = array[swapA];
array[swapA] = array[i];
array[i] = a;
}
//output random array, then mergeSort the array
print_array(array);
sort_array(array);
return 0;
}
//Get my array.Length
int array_size(int *array) {
return sizeof(array)/sizeof(array[0]);
}
//Output array
int print_array(int *array) {
int i;
for(i = 0; i < (array_size(array) + 1); i++) {
printf("%d\n", array[i]);
}
return 0;
}
//merge the array after sorting
void merge_array(int *array, int low, int split, int high) {
int sorted[high-low+1];
int a = 0;
int b = low;
int c = split + 1;
//iterate from beginning to middle and from middle to end in parallel
while(b <= split && c <= high)
{
if(array[b] < array[c])
{
sorted[a++] = array[b++];
}
else
{
sorted[a++] = array[c++];
}
}
while(b <= split) sorted[a++] = array[b++];
while(c <= high) sorted[a++] = array[c++];
int i;
for(i = 0; i < a; i++) {
array[i+low] = sorted[i];
}
print_array(array); //Print sorted array
}
//Sort the array
int sort_array(int *array, int low, int high) {
int split = ( low + high ) / 2;
if( low < high ) {
sort_array(array, low, split);
sort_array(array, split + 1, high);
merge_array(array, low, split, high);
}
}
最佳答案
return sizeof(array)/sizeof(array[0]);
上述语句的计算结果为 1
(假设 sizeof(int *) = sizeof(int)
,如 H2CO3 所指出的)。
尝试这样的事情,
int main() {
//Concerned with the integrity of my rand
srand( (unsigned)time( NULL ));
//A global, random length array between 1 and 100?
int *array;
int number_of_elements = (rand() % 100) + 1;
array = malloc(sizeof(*array) * num_of_elements);
init_array(*array, num_of_elements);
getchar();
return 0;
将元素的数量作为参数传递给 init_array
而不是每次都计算它。
关于C 合并排序段错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/14701255/