qsort

Can the qsort comparison function always return a non-zero value?

由 你离开我真会死。 提交于 2021-01-07 01:40:47
问题 An ascending sort callback function for qsort and bsearch on an array of int could look like this: int ascending(const void *o1, const void *o2) { int a = *(const int *)o1; int b = *(const int *)o2; return a < b ? -1 : 1; } Yet this function seems to violate the constraint on the compar function as specified in the C Standard: 7.22.5.2 The qsort function Synopsis #include <stdlib.h> void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)); Description The

Can the qsort comparison function always return a non-zero value?

由 拥有回忆 提交于 2021-01-07 01:39:47
问题 An ascending sort callback function for qsort and bsearch on an array of int could look like this: int ascending(const void *o1, const void *o2) { int a = *(const int *)o1; int b = *(const int *)o2; return a < b ? -1 : 1; } Yet this function seems to violate the constraint on the compar function as specified in the C Standard: 7.22.5.2 The qsort function Synopsis #include <stdlib.h> void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)); Description The

Can the qsort comparison function always return a non-zero value?

由 空扰寡人 提交于 2021-01-07 01:39:38
问题 An ascending sort callback function for qsort and bsearch on an array of int could look like this: int ascending(const void *o1, const void *o2) { int a = *(const int *)o1; int b = *(const int *)o2; return a < b ? -1 : 1; } Yet this function seems to violate the constraint on the compar function as specified in the C Standard: 7.22.5.2 The qsort function Synopsis #include <stdlib.h> void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)); Description The

qsort gives [Error] : invalid conversion from `int (*)(cricketer*, cricketer*)' to `int (*)(const void*, const void*)'

由 蓝咒 提交于 2020-12-26 08:03:48
问题 This is the code, it sorts the data of cricketers by avg runs. The qsort function is showing errors: [Error] C:\Users\Encoder\Documents\C-Free\Temp\Untitled3.cpp:29: error: invalid conversion from int (*)(cricketer*, cricketer*) to int (*)(const void*, const void*) [Error] C:\Users\Encoder\Documents\C-Free\Temp\Untitled3.cpp:29: error: initializing argument 4 of `void qsort(void*, size_t, size_t, int ( )(const void , const void*))' include #include<stdlib.h> struct cricketer //structure for

qsort gives [Error] : invalid conversion from `int (*)(cricketer*, cricketer*)' to `int (*)(const void*, const void*)'

由 丶灬走出姿态 提交于 2020-12-26 08:02:53
问题 This is the code, it sorts the data of cricketers by avg runs. The qsort function is showing errors: [Error] C:\Users\Encoder\Documents\C-Free\Temp\Untitled3.cpp:29: error: invalid conversion from int (*)(cricketer*, cricketer*) to int (*)(const void*, const void*) [Error] C:\Users\Encoder\Documents\C-Free\Temp\Untitled3.cpp:29: error: initializing argument 4 of `void qsort(void*, size_t, size_t, int ( )(const void , const void*))' include #include<stdlib.h> struct cricketer //structure for

sorting a linked list containing strings

由 青春壹個敷衍的年華 提交于 2020-05-30 13:11:49
问题 So what I want to do is to sort an linked list containing only strings. To do so, I have 2 options. Option 1 - dynamically allocate an array with the same size as the linked list and the strings containing it also with the same size, copy the contents of the linked list into the array and sort it using qsort . Option 2 - implement a merge sort algorithm in order to sort it. One of the problems is will it cost more memory and time if I do option 2 over option 1 or the option is the better? My

快速排序

由 孤者浪人 提交于 2020-03-20 21:57:37
3 月，跳不动了？>>> 1、思想 每次选出一个基准，然后将数组剩下的元素分为两部分，一部分小于基准放到左边，一部分大于基准放到右边。然后对基准左右两部分分别做同样处理，分治思想。 2、时间复杂度 最快 O(nlogn) ，最坏 O (n^2) ，平均 O(nlogn) 。 3、代码实现 //常规版 public class quickSort { public static void QuickSort(int[] arr){ QSort(arr, 0, arr.length-1); } private static void QSort(int[] arr, int low, int hight) { int pivot; if(low < hight){ pivot = Partition(arr, low, hight); QSort(arr, low, pivot-1); QSort(arr, pivot+1, hight); } } private static int Partition(int[] arr, int low, int hight) { if(arr == null || low < 0 || hight >= arr.length){ new Exception(); } int pivotkey = arr[low]; while(low <

关于 qsort 的一个坑

由 ↘锁芯ラ 提交于 2020-02-24 10:48:13
文章目录 系统里面具体解释如下 在使用的时候有几个问题 我们知道 c 语言有一个快排函数 qsort # include <stdlib.h> void qsort ( void * __base , size_t __nel , size_t __width , int ( * __compar ) ( const void * , const void * ) ) 系统里面具体解释如下 在使用的时候有几个问题 自己定义的比较函数必须跟给定的形式一样，然后在实现的时候在函数题内进行强制转换 int self_cmp ( const void * a , const void * b ) { int * _a = ( int * ) a ; int * _b = ( int * ) b ; return _a - _b ; // 从小到大排 } // 从大到小就 return _b - _a; 返回值必须是 int 类型的数据 int self_cmp ( const void * a , const void * b ) { double * _a = ( double * ) a ; double * _b = ( double * ) b ; if ( abs ( _a - _b ) < 1e-7 ) return 0 ; else if ( _a - _b > 0 )

Segmentation fault when using qsort and printf

由 偶尔善良 提交于 2020-01-25 20:58:06
问题 I'm trying to make a program to crack passwords by searching through a file of md5 hashes and using bsearch to find them in a rockyou database. My problem is that I'm running into a segmentation fault that is either caused by my qsort or my printf (I've run Valgrind and it says printf, but manipulating qsort changes the error output). I can't seem to find the solution online, though I've tried flushing stdout and different ways to size the array in the qsort function. char **dict = read_dict(

qsort_b and qsort

由 若如初见. 提交于 2020-01-22 15:04:33
问题 Writing a program that demonstrate different sorting algorithm in C++ on Mac. I found two quicksort implementation, qsort and qsort_b. The first one is of course the old-fashioned, seen-everywhere qsort. But there's qsort_b, which takes an block rather than a function. Here's my code: #include <cstdlib> #include <cstdio> #include <iostream> #include <cstdio> #include <ctime> #define DATA 1000000 using namespace std; int compare(const void* a, const void* b) { return *(int*)a - *(int*)b; } int
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