[英]using qsort function to sort a struct
所以我需要使用 qsort() 對包含結構的數組進行排序
#include <stdio.h>
// =========
struct pair
{
int encounters;
};// pair{}
int compaireEncounters(const void*, const void*);
int main()
{
struct pair* working[5];
working[0]->encounters = 10;
working[1]->encounters = 3;
working[2]->encounters = 1;
qsort(working, 5, sizeof(struct pair), compareEncounters);
int i = 0;
while (i < 3)
{
printf("%d \n", working[i]->encounters)
i++;
}
}
int compaireEncounters(const void* av, const void* bv)
{
int a = ((struct pair*)av)->encounters;
int b = ((struct pair*)bc)->encounters;
return(a > b);
}
我正在嘗試獲取 output:
1
3
10
但相反,我得到了一個分段錯誤核心轉儲。
這里有什么問題?
在取消引用指針之前,您必須將指針分配給有效緩沖區。
在這種情況下, working
應該是結構數組,而不是指針數組。
也不要忘記初始化所有要排序的元素。
您的代碼中還有更多錯誤:
qsort
時不包括正確的 header ( stdlib.h
)compareEncounters
用於main
function。printf()
語句后缺少分號。bc
用於compaireEncounters
function。固定代碼:
#include <stdio.h>
#include <stdlib.h>
// =========
struct pair{
int encounters;
};// pair{}
int compaireEncounters(const void* , const void*);
int main() {
struct pair working[5];
working[0].encounters = 10;
working[1].encounters = 3;
working[2].encounters = 1;
working[3].encounters = 334;
working[4].encounters = 42;
qsort(working, 5, sizeof(struct pair), compaireEncounters);
int i = 0;
while (i < 3) {
printf("%d \n", working[i].encounters);
i++;
}
}
int compaireEncounters(const void* av, const void* bv){
int a = ((struct pair*)av)->encounters;
int b = ((struct pair*)bv)->encounters;
return(a > b);
}
如果要使用指針數組,
qsort()
的元素大小。compaireEncounters
以比較指向結構的指針。#include <stdio.h>
#include <stdlib.h>
// =========
struct pair{
int encounters;
};// pair{}
int compaireEncounters(const void* , const void*);
int main() {
struct pair* working[5];
working[0] = malloc(sizeof(*working[0])); working[0]->encounters = 10;
working[1] = malloc(sizeof(*working[1])); working[1]->encounters = 3;
working[2] = malloc(sizeof(*working[2])); working[2]->encounters = 1;
working[3] = malloc(sizeof(*working[3])); working[3]->encounters = 334;
working[4] = malloc(sizeof(*working[4])); working[4]->encounters = 42;
qsort(working, 5, sizeof(*working), compaireEncounters);
int i = 0;
while (i < 3) {
printf("%d \n", working[i]->encounters);
i++;
}
}
int compaireEncounters(const void* av, const void* bv){
int a = (*(struct pair**)av)->encounters;
int b = (*(struct pair**)bv)->encounters;
return(a > b);
}
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